+1 for coinbase. As long as you transfer the bulk of your coins to an offline wallet (Electrum is pretty simple), you can buy from any exchange like this pretty safely.
I've been doing dollar cost averaging through coinbase for the last three months (buying $20 worth every week), and with the recent surge my ~$300 investment is now worth over $1,000.
Eh, I wouldn't recommend Coinbase. They deemed one of my purchases from them as "high-risk" and have been holding my money hostage since. Support team has been taking 3-4 days to reply to each email in the thread.
They've been chalking that up to growing pains -- for the longest time, they didn't even have a dedicated support guy hired; it was just the two founders. Last time I checked they had just one member of staff dedicated to support, although by now they might have one or two more.
I've been doing dollar cost averaging through coinbase for the last three months (buying $20 worth every week), and with the recent surge my ~$300 investment is now worth over $1,000.