I have to agree. Have a read through and bookmark the various AP builds. Look and see what others have done and then at some point jump right in.
For me I went with helmet first. I wanted the soul of the kit to come from the classic stormtrooper helmet. From there I picked off a few easy things like hand plates and TD. At some point you're gonna have to move into harder territory and size, mark,measure, measure, cut, barf and repeat for the limbs.
Good luck!