The security of bitcoin circles in the private key that there is no way you can just guess off. But as a precaution, ensure that your computers or phones are cleaned from hackers that wants to know what inside your wallets. Don't easily trust any links that send to you or any suspicious promises that is too good to be true. Remember that this is a market, and investment is all a lot safer with patience and a lot of time. So keep your faith up and hold your coins.