IF you buy through an exchange, withdraw the coins and store them in your wallet (do not leave them sitting in the exchange). If you are day trading or something, then you have to risk it if you do not want to miss big gains (ups and downs happen too fast, this mean by the time you send your BTC from your wallet to the exchange, the party would be over). But I think you arent interested in this and you want to just hold, so yeah, buy withdraw and hold.
You can also use LocalBitcoins.
All of this makes sense when the bitcoin price is going up but these days it's going down.
What you should do is hold off on buying. Buy when the price has bottomed out. You'll know when that's happened when it stops going down and starts going up again and keeps going up. That's when you buy.
If you've already bought then sell it and wait for the above to buy back in.