Back off on the fertilizer. Remove dead damaged or diseased wood at
any time.
Make pruning cuts to the branch collar not flush with the trunk or
thicker stem.
The branch collar is the swelling just before the branch joins the
trunk, you want your cuts to leave that knob of wood because that is
where the tissue that will make the bark to heal the wound is.
Look on the undersides of the leaves for scale insects while you are
working.