I 100% with Juvins, I feel a lot of people starting affiliate marketing have unrealistic expectations. Any beginners to affiliate marketing will watch two or three YouTubers and expect to make the same amount as someone with hundreds of thousands of followers. If you are starting from scratch you should aim for affiliate marketing to just be a passive income for at least 6 months.
The key to not failing affiliate marketing the first time is pretty simple, just pick the best affiliate program that fits your content and be constant with your content.