Ask yourself: "Did i do anything, now or in the past, that violated Reddit's TOS?" If the answer is yest, that's the reason your subs get banned. But only you know what you did.
Now you should ask yourself the question: "How do i stop them from finding out i was previously banned?"
Also, don't do aggressive actions on fresh accounts. Don't create subreddits, don't post too often, don't upvote too often. Most Reddit newbies don't go on to create a subreddit and start promoting it as soon as they create a new account. That's usually seen as a red flag and it will prompt the system to look a bit further into you.
