Weeeellll... Everything? Who will ever know everything about cryptocurrency and "right investing"? True, it's important to stay informed and to do your own research, but more importantly, know what your goal is.

Do you want to day-trade?
Do you want to buy crypto and use it for stuff (tickets, electronics, ect?)
Do you simply believe in the ICO project and want to HODL?

Far as I am concerned, there are a few basic rules:
- Start small, get familiar with the market
- Diversify (so, don't "only" go for Bitcoin, but maybe take a look in other cryptos or investment options as well?)
- Keep track of market movements
- Don't make decisions based on emotions (often people create a hype on media / telegram ect..).. Do NOT fall for it
- Don't lose your nerves when trading Bitcoin (or any crypto). Yes, it will go up and down..but if you panic-sell, you're only making it worse.

I'd suggest taking a good read at the various crypto info-sites, if you want to get a better picture.

Found a really beginner-friendly explanation (in a few languages) about Bitcoin investment tips :Here

Good luck!