There are 3 basic things everyone should follow.
1. Dont invest money you cant afford to lose. Cryptocurrency is extremely volatile in comparison with other assets thus very risky.
2. Buy low, sell high. Its logical and seems easy but in fact, its very hard to identify the peak price of the crypto and sell it when the rest crazily buy it
3. Dont put all eggs in one basket. By buying different crypto coins, you reduce the risk of losses.
Then youll need to determine what cryptocurrencies you want to trade taking into account their technology, concept, supply, market cap, etc. Find trusted and reliable crypto exchange that accepts credit card or bank transfer like Cex. It allows trading both fiat to crypto (
https://cex.io/btc-usd ) and crypto to crypto.
Practice trading and learn about cryptocurrency as much as you can. Cryptocurrency is a very sensitive thing that doesnt like weak hands.