With offsets you will become more adept at figuring it out on the fly, placing an object, running to see if it is in the right place, adjusting etc. The debug menu also has a sprites position relative to 0,0 which might help you also. Grab the Tiledbackground texture from the cap, and place it down on your background, each square is 32x32 so you will have a good idea where you are at right away.
Clamp is awesome, it really simplified a lot things for me. Quazi or his brother introduced clamp to me somewhere a long the way, and once you find it, you will find a lot of places to use it.
Clamp(a, b, c)
a is where the value changes. b is where the bottom limit of the change to value a, c is the upper limit of the change to value a.