So as a new proud Mac owner there's a lot of new stuff I'm getting used to. One of which is finding the best way to keep my iMac backed up. Do I use a offsite service like back laze or crash plan? Do I roll with my own external drive? How big of a drive should I get? Which one? If anyone can offer there advice or tips, I'd greatly appreciate. I was thinking of maybe just getting a WD My Book 4tb external desktop drive and use that. Is that too much space?