There's a lot of things you need to consider that if you don't give importance your investment may be at risk so here are some of the things ou need to consider or to study.
Learn about the basics first such as:
Bitcoin wallets
How Bitcoin works
What is Blockchain
Types of wallet
And different kinds of investments
Second Learn what kind of investments you need to do, here are:
Trading
Holding
When you've decided what kind of investment you're going to do start finding exchange where you will bought your first bitcoin there's a lot of platforms where you can buy bitcoins such as:
LocalBitcoins
Binance
Coinbase
Just search on the internet.
NOTE: You should know the risk you're going to face when it comes to investment remember that there's no assurance that if you invest you're going to earn so invest only what you can afford to lose.
Why do I play BTC in particular and coin in general? I like to count "gambling" in this "investment". I do not need the stability, stability of gold, ForeX or stronger than CK. I like it most is the sunshine in the afternoon rain: 6k pm 7k, the morning before 8k 7k, eat loud and die big. It is the "gambling" nature of it, the opportunity to eat more for the winners, the bitter end for losers. If BTC is stable, I immediately leave this market and move the investment, it's new "stable" 2 days I was tired of it. So stop stop BTC stable for me, believe me, if it goes smoothly and stable with extremely small amplitude, most of you also withdraw funds to other fields (Because there are too many fields Volumes are big and protected again. "From where to go to that", you join the coin for speed of a crazy amplitude, when that is no longer, then keep you.