I've been interested in this space for years and have really started to trade more over the last 6 months (like a lot of people) but here are the rules I've come up with. I know it's not very scientific, and it's risky, but in this space everything is risky!
1 - don't invest anything you're not willing to lose. I had credit card debt, and put 100 into bitcoin a few years ago. I sold it this August to make me debt free and started investing 2% of each paycheck.
2 - check coinmarketcap only once per day. It will drive you crazy and you won't see trends if you check it too much
3 - read reddit - a lot of shill posts, but if you see something pop up consistently it's worth looking into and possibly buying.
4 - everything dips, and it's great to buy the dip. But if you want to buy a coin, I recommend buying it in three steps separated by 2 days each.