1 height: stand straight, from head to ground
2 inside leg/inseam: straight leg, inner thigh to ground
3 arm length: elbow bend in a right angle, shoulder cap to sleeve length/wrist
4 chest/bust: find the point with the biggest girth
5 waist: point of smallest girth, above the belly button (remember you still wanna be able to breath in your cloth, so theres no point in holding your breath while taking your measurements)
6 hip: find the point on the biggest girth
of course there are a lot more measurements you might need for something you wanna sew, but those are the main ones.
all the best