You don't. Hacks target the exchanges wallet by finding exploits and not the user accounts separately. If you want your funds to be safe, use exchanges for trading only and withdraw to your personal wallet.
it makes me little scare sir, how about the wallet? it's still safe?, if you have any recomend ,what's good exchanges sir?
There is nothing like a good exchange. If you are holding for the long term, you can decide to go the cold storage way. If you do not have the cash for stuffs like ledger Nano, you can just generate a paper wallet and your public key is the only thing you need to always receive funds.
As long as you are not trading, never leave your funds in an exchange and even if you are trading, make sure your account security is sound enough.
One thing is to always make sure safety is paramount when it comes to cryptocurrency just like the OP stated. We cannot always avoid some of these things, but the earlier people started knowing how to stay secured, the better. Expert hackers or not, if you leave yourself vulnerable to an attack, you will definitely be a victim and the best is to always be on the lookout, most especially for any phishing links.
Hackers are everywhere and all the hackers which are there in this world are actually keep on trying their best in order to get access over the others account so that they can make some money out of it. This is seriously one of the greatest threat which almost all of us are afraid of and most of us have also fall victim of such kind of activities. The thing is it is only the knowledge about the things which can save us from such kind of things.