Starting out on reddit can be intimidating because it seems chaotic, but the key is understanding that each community is its own world, the first thing you should do is find three or four subreddits on topics that genuinely interest you, don't join fifty at first because you'll get overwhelmed, once you're in, dedicate a week just to reading, pay attention to what kind of posts get the most upvotes, how popular comments are written, and what the rules are for each subreddit, which are usually posted at the top.
After that week of observing, start commenting, don't rush into posting yet, comment on things that contribute, don't just say good post or I agree, add something of value, share a personal experience, or ask a question that continues the conversation, funny or very helpful comments are the ones that get the most upvotes, avoid posting links to your blog or channel because you'll get banned immediately, reddit hates spam with all its heart.