Starting with the bottom hinge remove the hinge screws on the door first and insert the shim between the hinge leaf and the door.
Fix gap on side of door between lock and door.
Open the door and place a wooden block or hardback book under the outer corner of the door to hold it in place while you work.
Frost king corner guards.
This will shift the top half of the door upward.
Http bit ly frostkingcornerguards ks door corner seals white.
If the gap along the latch side of your door is allowing unwanted air to infiltrate your space or letting expensive heat or cooled air out weatherstripping can help reduce or eliminate this space.
Remove the trim and cut the nails holding the frame to the studs.
Place the shims between the hinge leaf and door at the bottom and middle hinges.
A gap between the bottom of the front door and the threshold is easily fixed with a door sweep.
Open the door and place a support or wooden wedge under the door to relieve tension.
If the hinges are fine you may need to take the door off and re square it from scratch.
If that doesn t work shim the hinge side.
If the screws are loose in the casing replace them with larger ones to create a tighter fit.