Many have answered this question before me, and my first piece of advice would be to do your research and take advantage of the resources others have already created. These established professionals offer better advice than I can.
Yet, this is still a frequent question in my DM's, so I'll add my perspective and opinions, based on my own path.
Know the Risks
I would not recommend this job to most people. Banks are allowed to close your account and seize the balance, even if you did nothing illegal. Your porn may be pirated. You may encounter fake producers (always ask for and verify references!). You might not get booked enough. Agencies might leave ou unbooked or send you to sets you don't like. People will likely leave mean comments, and share your porn with offensive commentary. People might mock, fetishize, or misrepresent parts of your identity or body (race, disabilities, gender, age, etc.) Friends and family may recognize you. Old enemies may out you. Payment apps , social media sites, and dating apps may ban you. Social media sites may tie your personal to your performing profile using facial recognition or IP tracking. Future vanilla jobs may turn you down.
Given the pattern of recent laws passed to fight "sex trafficking" (with no differentiation between consensual or even legal sexual labor, and slavery), and given the recent surge of technology built to compromise our privacy, these risks will likely multiply in the coming years. Before allowing yourself to be filmed, and signing any paperwork, be sure that this is something you really want to do.
The good news? You're highly unlikely to contract an STD on-set.
Get Tested
Before you exchange fluids with any other performer on camera, get yourself tested according to industry standards, within 14 days (or less) of the scene. Go to TalentTesting.com or Cutting Edge Testing to sign up to get tested at a lab near you, and have your results sent to the PASS system so that others can verify your status. This will cost about $150-$200, and isn't covered by insurance. Other STD testing sources have different standards, and aren't verifiable against forgery the way the PASS system is. Following industry standards is important for a professional reputation, and for the collective safety of our industry.
Before filming, log in to PASS or Talent Testing on your phone, and watch your scene partner do the same - verify that it's the real website and not a screenshot, and that they are cleared through PASS with non-reactive results. This prevents forgery and ensures safety.
Practice safer sex outside of scenes and use barriers (condoms) with people outside of the PASS testing pool, and/or wait to hook up for fun until you don't have filming coming up, and before your next test.
Do it Yourself
From my view, the most reliable way to break into the industry is to do it yourself. It can take a substantial time and money investment, and profits generally start off slow, but creating and selling one's own videos is doable and accessible to those willing.
I recommend starting with high-quality images and footage of yourself, ideally showing your whole body and face. This gives other performers or producers that you might want to work with an idea of what to expect before you get a chance to build your reputation face-to-face. The following skills and equipment can also incentivize other performers to work with you.
Learn the Right Skills
Self-producing will require many skills to research, learn from a professional, or outsource. The more skills you can master, the more control you can have over your career, and the more valuable you will be to others in the industry.
Performance: This is hard to explain in a paragraph, but it matters. Stamina, understanding of angles (body, camera, and lighting), flexibility and agility, hygiene and presentation, acting, presence, physical talents, and more make certain performers stand out from others.
Videography: Anyone can record video with their cell phone, but investing in a higher-quality camera or professional lighting, and learning how to best use it, can increase the quality of your content, add to its selling value, and incentivize others to work with you. Professional videographers can be hired by the hour, and there are many in the industry who will work on a content-trade basis.
Storage: Videos can easily become huge files, and you will need external hard drives. 1 TB is good to start. They are breakable if dropped or shaken, so be sure to save each project in at least 2 locations and handle with care.
Editing: iMovie and Windows Movie Maker are free, and enough to combine videos, music, and text to complete a simple project. Learning to use higher-power or premium software can also offer more control and special effects, and compensate for many recording issues. This may also require upgrading to a gaming computer or one equipped for video editing, especially 4k. (though I use an inexpensive Lenovo Yoga that's equipped for 4k and runs Adobe Premeire Pro fine). If you'd prefer to outsource, I offer video editing services for flexible prices (and an indie performer discount) or for content trade.
Marketing: Learn best practices for different selling platforms, ad opportunities, web maintenance, SEO, and social media marketing in order to maximize sales. (See "Get Help" below for more advice on this)
Networking and Professionalism: As in most professions, it makes a difference to show up on time, perform as expected, have a pleasant attitude, respond to direction, give a strong effort, take tasks seriously, as well as give a great show. Making a good impression professionally behind the scenes is one of the most important ways to gain trust and respect as a new face.
Legal: The adult industry is heavily regulated. Familiarize yourself with 2257 requirements, model releases, and entertainment contracts. Collect photos of ID's and of the performer holding their ID.
Pick Your Selling Platforms
These are just a few platforms that I've used. Choosing multiple platforms and diversifying income streams is often the most sustainable path, exposing your content to the widest audience. Signing up via the links provided will add you to my affiliate network, and I would be happy to chat about the platform with affiliates and promote your work as able.
ManyVids: MV is an established but cutting-edge clip selling site that stands out for its ease of use, many earning options, and high traffic. You can sell videos, photo sets, store items like panties and prints, video subscriptions, mailing list subscriptions, custom videos, and chatting, live cam, make money on free video views, and more. Stores are easy to set up, and the site brings in a heavy native traffic that's helpful for beginners.
IndieBill: At 85%, IndieBill offers one of the highest payouts available. However, its site brings virtually no native traffic, so it's best for directing your own traffic from social media or your own website. The check-out page is simple and quick for efficient conversions and a payout rate that adds up fast.
AmateurPorn.com: AP has limited but some steady native traffic, and a high 75% payout rate across the board. The custom clip ("BTO") option is one of the most intuitive in my opinion, and bundles are a unique option. It's very easy to use.
iWantClips: IWC has limited native traffic and a market oriented towards femdom content. Its preview generator, which creates both short video clips and GIF previews, sets it apart.
BitVids: BitVids is a new, easy to use platform using bitcoin exclusively.
OnlyFans: OnlyFans is a highly popular subscription site offering 80% payouts, but it's also popular among pirates.
Get Help
Find those whose careers you'd like to emulate (not just who you want to bang, I mean), research as much as you can, and aim to build a positive and professional relationship.
Seek out Experienced Performers
You stand to learn far more from someone who's seen plenty in the industry than from someone who's just starting out (like me, honestly). It can be more intimidating to create these connections, but they can be the most valuable. Many established professionals focus on working with new talent.
Pay for Advice
Many don't have the time or DM space to engage with every curious person who reaches out to them, and the probes are often insincere. However, many do offer advice and consultation for a fee. Examples are Amberly Rothfield and Ellie Boulder.
Signing up for a selling platform through a model's affiliate link is another way to compensate an established performer at no cost to you - they either get a referral bonus from the site or an extra percentage of your sales - and incentivize them to help you grow. I've provided affiliate links above and am happy to chat with folks who sign up through one and actively use that platform.
Keep Researching
Find inspiration in the industry. Follow them on social media (Twitter is best right now). Many industry folks write articles, blog, vlog, podcast, present lectures, appear in interviews, and more. Seek out their voices. Research your favorite studios. Scour websites. Follow adult industry news sites and unions. Keep up with current laws. There's always more to learn.