I am not an expert but I also want to share my experience I gained here in crypto community. Before you start buying and investing bitcoin, you must learn first the basic as what they have posted above. It is very important to have knowledge before taking any action in unfamiliar thing. Don't forget to use only those legit and trusted services or any third party apps.
Don't be fooled from users offering you HYIP/ponzi scheme/doublers, it will only cause you trouble and losses while they're getting your money.
Aside from bitcoin, there are altcoins. You can look for a reference like CMC (coinmarketcap) and CoinGecko which coins/tokens are on top of market cap and worth investing.