Starting out in affiliate marketing depends on the chosen vertical, your budget, and your willingness to learn from mistakes. Beginners are almost always better off starting with the "goods" vertical (physical products/e-commerce): it is hard to run at a loss here, yet you quickly master basic skills—generating campaign setups ("funnels"), creating test ad creatives and copy, and gaining experience in launching traffic and analyzing it (the latter being the most crucial skill for a media buyer).
A decent ROI in this vertical starts at 20%. Popular offers in many GEOs are often already saturated, making it difficult to turn a profit (so always ask your manager about fresh new offers).
The main advantage of this vertical is the simplicity of launching campaigns and the lack of moderation issues. Cloaking isn't required, so you can save money there.
At the start, focus on your ad creatives. Spend plenty of time analyzing spy tools, but make sure to create the actual ads yourself—this way, you’ll understand what drives the audience to click and buy. Be sure to track traffic using a tracker and postbacks. Dedicate a few hours daily to reports and analytics.
If your budget allows and you want to get up to speed faster, you can start with the "nutra" vertical (health and beauty products). There are many offers, and fresh ones that offer real earning potential appear constantly. Testing 10–15 campaign setups per month will cost roughly 1,000-1,500. Be prepared: most setups will turn out to be unprofitable. Even experienced media buyers only see success with about 20% of their campaigns. Factor in an additional 300-400 for overhead costs: anti-detect browsers, trackers, card top-ups, and spy tools. For a proper deep dive, it is recommended to spend 2–3 months running continuous campaigns while constantly learning from your mistakes. If you haven't turned a profit by the end of this period, it’s probably best to call it quits.