Thanks guys for giving me good advice. I guess I have to buy a hardware wallet.
Yes. Hardware wallet is one of the safest options out there if you use it properly.
Investment in such is very low if we see what are the potential losses in case of attacks.
Though we say Hardware wallets are fully secure but not a 100% assurance that our coins still be safe forever. However, it is much secure than of saving our holding in online wallets cause it is very prone for hacks and losses of private keys especially when we are using internet cafe. It is recommended that we should used our own PC and we should be careful in visiting sites especially involving eth address and keys.