Use an Electrum or Multibit. With any of these two, you can't go wrong. Of course that the safest is Bitcoin Core but is also very resource hungry. You won't lose much with Electrum for example in the terms of security, but you will gain a lot of computer usability, especially if you have older machine.
Don't use online wallets though. Online wallets are not as safe and you don't control your funds which is one of the Bitcoin strengths. You are pretty much believing a third party (online wallet providers) on keeping your coins safe.