External hard drive

Hi everyone,

I have a MacBook Pro 13 inch. I know that I can take an external hard drive and put into it apps and files and use the apps when they are on the hard drive (currently doing this with my Mac Mini. Connecting the two computers with thunderbolt cable and the Mac Mini is on the target disk mode). I also want this hard drive to be portable. How can I know if the hard drive is good for my needs? Any suggestions?

Thank you very much,

Amit Inbar.