Waist: jeans should sit comfortably without a belt and without digging in. You should be able to slip one finger between waistband and skin.
Hip: the back pockets should sit centered on each butt cheek, not too high or low. Side seams should be straight, not twisting.
Thigh: depends on cut. Skinny = formfitting but not restrictive. Slim = some space, no pulling. Straight/relaxed = drapes without bunching.
Length: skinny/slim should hit at the ankle bone. Straight should break once at the shoe top. Bootcut should cover the heel of the boot.
If the waist gapes but the hips fit, you have a curve mismatch. Try a curve-cut brand (Levi's Wedgie, Madewell Curvy, Good American).