1) Do no use public computers nor computers that are used by more people.
2) Always have an up-to-date antivirus program.
3) Always protect yourself with long passwords and do activate the 2FA (two factors authentication) whenever you have the possibility. (DO NOT FORGET TO BACK UP YOUR KEY)
4) Double check each time the web address you access, phishing methods are extremely dangerous and you are vulnerable. Do not click on websites links sent by other people. Do not be fooled by slack messages like: "Attention there was a hack on your myetherwallet, please access: email@example.com and get your wallet up-to-date." You are going to input your valuable log in details into a fake website and got them stolen.
5) Avoid groups that guarantee you "pumps" or trading strategies that bring you "900% return". Avoid people that manipulate the market or offer you profitable trading strategies in exchange of money (there are some professional our there that do this kind of things, but be carefully because the rest 90% are scammers")
6) Keep your tokens on trustworthy exchanges or preferable on hardware wallets powerfully secured.
7) Do not use shady exchanges or send your tokens to unknown people in exchange for services or promises.
8) If you ever feel unsafe about something do ask somebody you trust about what is the right decision. There are people that have more experience than you and they can give you some pieces of advice if you need. Just ask!