What playr158 said...
My suggestions are to ensure that the title is clear and in the person who you are buying the bike from's name. Stay away from a salvaged bike in spite of what the alleged cause of the loss was. You never know what problems you could be getting into with a salvaged bike.
Learn the controls and make sure all electrical controls work.
A few weeks ago I took the MSF course in order to waive the riding test at the DMV and highly encourage anyone who wants to ride a motorcycle or who even has an interest in riding to take the class.
I am not a huge guy but at 6'1 i felt uncomfortable on the little Ninja 250's we had in class so i rode the cruisers instead. I felt a lot more comfortable on my friend's 2002 Honda CBR 600 F4i, which i have been riding around a little bit here and there for the past few months, and am actually highly considering one as a first bike for myself. My intentions are to ride track mostly(after classes) and occasional highway to my parent's house(100+miles away) so a 250 doesn't really suit my needs as sufficiently as a 600 would. The Suzuki gs500f and Kawasaki Ninja 650r are also 2 bikes i am considering.
Here is a forum that has a lot of the questions that you might have and has them answered already
Sportbikes.net I suggest that you read most of the stickies.