Remember - the time spent in preparing the piece will be reflected in the finished product. Anything loose must be reglued. Use yellow wood glue and clamps. Glue is a bonding agent, not a wood filler. Joints must fit together tight. All old glue must be removed to insure proper penetration of the new glue. Don't use epoxy glues on joints that may need disassembly later. If you lack clamps, apply pressure with weight or a tourniquet. Tape cardboard over contact points to prevent damage. Use a 2 part glue on teak, rosewood, or other oily woods. Dark water or stain marks can often be removed with oxylic acid. Mix crystals in warm water until no more will dissolve. Apply solution evenly over entire surface, not just the stain. Reapply as needed.
Important - sanding will release an acidic dust into the air that is harmful to breath. Wear a dust mask! Before sanding, use steam to raise dents. Lay a damp cloth over the dent and press lightly with a hot iron. Let the steam penetrate, remove the cloth, and allow to dry 10 to 15 minutes. Repeat as needed. If the wood is rough, begin sanding with 80 to 100 grit sandpaper. Finish sanding with 150 grit if you intend to use a stain or dye. Finish sanding at 220 grit if you are staying natural. If you have an orbital sander, check that it's OPM rate is 10,000 or higher. If not you may leave sanding scratches. Sand with the grain, being careful not to sand through any veneers. Slightly round any sharp corners or edges.
Finish by block sanding all flat areas to correct any waviness or dips. Cross grain scratches will be difficult to see now, but will show up after finishing. Round, turned legs and posts may be sanded with Scotchbrite or a sand-a-flex machine. After sanding with either, go back over lightly with sandpaper with the grain.