Personally, I use metamask (a software wallet) to start trading. Later on, when I became more and more into coin trading, hardware wallets become a necessity for better security. In short, wallets help you keep the private keys at a safer place. Software wallets like metamask are safer than centralized exchanges. Hardware wallets are even more safer than software wallets for another layer of isolation. I used ledger nano s. Trezor is equally great. I also wrote an article on 0x which may be helpful to you.