I have a 2000 Chevy Blazer with a door sag?

i have used a floor jack to hold the door up and changed one door hinge

at a time its easy

easy to replace door pins and bushing cheap too but woul dbe easier if you had one friend to help hold door up but ive done it a lone not so hard to remove but holding up and trying to start a screw a pain pins just drive out bushing just tap in that part easy an dif you watch or mark where hinge is before helps you line it all back up most likely any parts store carried door pins an d bushing for it

Johnny has the right idea but when you use a floor jack also use a 2x4 or a 2x6 on the jack to help protect the bottom of the door

you like a particular spring compressor device. while you're good at making issues you may desire to construct one your self curiously variety of like a series of salad tongs approximately 12 inches long with a bolt approximately 0.5 way between the hinge and the tip that holds the spring.

it all depends on your knowledge and skill level, honestly it is not that hard to do if you pay attention to what you are doing