Before you dive in, you have to make evaluate your risk-taking ability.
There are 2 ways to invest into BTC, or any crypto in gernal.
1. Trading
2. Mining
Trading is risky, it requires a lot of study and the market change can wipe out all your investment over night. Obviously we know how volatile crypto currencies are. I’ve traded BTCs in the past and wouldn’t recommend this at all.
I find mining to be a better option. I use RRMines services. Their decentralized computing power platform has a variety of products, In addition to the 3-year long-term contract, lock-in period of 30 days, 90 days, 180 days are also available. After the end of the lock-in period, users can freely trade or renew their computing power contracts. The contracts can be transferred to other users or repurchased by platforms then users can recoup their costs for buying contract. A fixed investment will get you a more stable income, and you can choose to sell mined BTCs when the price is right for you. They've a large userbase of 100,000+

I Always use their 7 or 30 day lockdown option. You pay $13.99 for 7 days, the mining profit will cover your cost for purchasing the computing power and with a small extra as net profit. Not a lot of money, but its just the starter pack for you to learn the rope and decide if you like this form of investment. Trading to make profit is for professionals. Normal people without background in trading will almost always lose money. Cloud mining is less risky and more stable.

PS: I've no affiliation with them, I'm just impressed with what I use and I hope this helped you