A couple of things to loom out for
1. Make sure the seal is in the outside of the weather bar. If it's the other way around water flowing down it will puddle inside. Nit much you can do about it if that happens.
2. Try to place it such that the hinges as mentioned before AND the sash / lock is also not interfered with. If you have to break the run of the seal around the door, the draft from the break is very noticeable.
I normally place them c 1/8" inside of the rebate, this I have found to be the optimum for ta outing the hardware and ensuring that the door closes properly against the seal.
Last point, make sure you cut the seal groove such that the wipe is on the right side!!