Hey guys, I'm looking to buy a mustang from mid '60's-early '70's, but I'm not sure what to look for, interms of the body so I get a good deal and not a peice of junk. I'm looking at getting something that I can infact fix up myself as a project and then drive the car I've always wanted.
If anyone could help me out, that would be terrific!  

Rust.  Ford did not spend much on protecting the cars, so they rust.  Some worse than others, just depends on where they lived and how they were cared for.  Look in the trunk wells, rear wheel wells, tail end of front wheel wells, lower corners of the doors, under the carpet and front frame tails.  Look for previous repairs, like tacked in front floor pans.  If you find that, start looking hard elsewhere for repair work.  Use a paint thickness tool to look for bondo on the car.  The cowl is a source of a lot of water intrusion if (when?) the vent hat starts to rot away.  This is an extensive repair job - you can search this site for an article on it IIRC.  You don't have to be a trained body person to spot slip-shod work - it kinda stands on its own.

Get the VIN and door tag info off any potentials and run the numbers.  If you want - say - a real S code car, then it's important.  Also important if someone is trying to boost the price with some special claim on the car.  If you just want to have fun, you don't really care that someone put a 390 in place of a 302, unless they want an extra $$$ for the motor being there as in "oh, it's a 390 car that makes it worth more", etc.  

Buy based on your ability to fix problems and working space, but it's always best to get as complete a car as possible.  Paying extra for a complete car in good shape is money ahead.  Yes you can buy darn near everything to fix one, but it runs into bucks and repair bucks take away from the fun bucks.

The later models - 67 up - have better safety equipment, things like collapsible steering columns (68+), dual master cylinder, etc.  68 up should have provisions for front shoulder harness even if they are not installed.  Disk brakes are also an easy swap on these cars.

Someone will chime in with more, I'm sure.  

Thank you for the help. I have a question though, where would I search the VIN number up, sorry for the awkward wording  

It is definetly worth spending a little extra money up front to buy a solid car to start with. Unless you have the time, money, ability, space and tools to do a complete ground up, don't bother a so-so car. If you see a little rust hear ot there, there will be more hidden rust. Aftermarket parts seldom fit 100% properly. Other than that, do not be afraid to make the car what YOU want.  

VIN should be on the radiator support, under the fenders, later models will have it at the base of the windshield - driver's side.  Also the VIN tag and option data should be on the driver's door jab.  Later models (70 up?) use plastic stickers that can fade out or get painted over.  There might also be a buck tag somewhere on the radiator support - it's flat metal and black and might be a bit hard to find, maybe around the passenger side front near the headlights.