Hi, nice to hear someone new asking before jumping straight in. Short .com names are where you need to be. Your question is not easily answered as it depends on YOU - what your budget is, where your strengths are, what you like and have knowledge of and what you plan to do with the names.
I would highly recommend spending as much time as possible reading this site, Newbie section, Appraisals, etc etc, there is a lot of information here and in a weeks time you will probably see things differently than you do today.
A tip from me would be, don't buy 10 buy 1 and make sure that 1 is something you know about or have an interest in, i.e. instead of buying 10 names with $500, buy one name - quality not quantity.