Rust areas: Windshield frame near cowl and top of frame, Bottom edge of doors and rocker panels, floor pan check under carpet in footwell near front edge where door is and check rear around inner rear wheelwells and at rear corners on inside of bed. check around body mounts under the vehicle for rusted out crossmembers and definately check the rocker boxes under the vehicle. Look at door hinge areas on both the fender and front edge of door.
On the top look at the connection points at the front of the top above windshield, the under side of bedrail if it is a double wall the bolts will go in from bottom, if single wall they go in from top, check for cracks on interior of top along side edges above bed rail and look at rear door for cracks around hinges, also see if latch works.
I would recommend having a wire brush, safety glasses and a magnet to check for bondo on the body.