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.
You don't need to learn much about bitcoin nor its hard to invest with it. Trade is not the only option where you can buy bitcoin there's still some more way to earn. The most and easiest way to get benefit with bitcoin is holding. You don't need to understand any other things. Just do 3 steps and you'll get benefits. Choose a best wallet make an account on on it. Buy bitcoin and save them in your wallet and the last step is apply patience and completely forget about your coins and done. There's nothing hard to get benefit from bitcoins.