1) Make sure that it is a 2.5” Laptop drive (of course). 2) If you are looking for speed in accessing files, get a more expensive 7200 RPM drive, If you are trying to save money, get the average 5400 RPM drive. 3) Try to get one with at least 4mb cache, otherwise it will be slower. As long as you go with a trusted brand, you should be fine. I prefer Western Digital over others, but Seagate and Samsung are good too.