I usually find that the caliper slide pins are the culprit. Lots of places condemn the caliper first without checking the slide pins.
Also on a lot of older vehicles the rubber brake hoses collapses on the inside causing a sticky caliper.

I would first check the slide pins and see if they move freely. If they feel sticky, pull the pins out, clean the insides where the pins go with some penetrating oil, wd40 or whatever( I use a bore brush to get the gunk out)
then lube up with brake caliper grease.

To check if your caliper is sticking try to compress the piston in and se if it has a lot of resistance. If it feels like a lot, crack open the bleeder screw and try it again. If it gets easier you have a bad brake hose.
What I usually do when I compress the piston is peel back the rubber boot a bit with a pocket screwdriver and squirt some wd40 around the piston- helps lube up the oring.

To rebuild the caliper its a matter of finding the parts kits for them-o rings and seals.There easy to do.
Of course take the caliper off,take out the bleeder screw,put a block of wood between the piston and caliper where the pads sit-KEEP FINGERS CLEAR- and blow compressed air into the bleeder screw hole till the piston pops out.
Take the old oring and boot off,install the new ones. Also check the inside of the piston bore for rust or scoring.If theres scoring,you might be able to hone it out if it's not to deep.If slightly rusty take some 600grit paper and buff up the inside of bore.Lube up with light grease and re assemble.