1/ Make sure new strings are 'stretched in'.
2/ Pencil graphite in the nut slots and if you use heavy gauge make sure the strings are not snagging in the slots.
3/ Neat windings on the machine heads, follow the 'rule book', lots of info on the net.
4/ Fully tighten the trem tension screws (if you can use it this way) instead of 'floating. This way the trem always returns to point zero everytime.