Most useful one is /chotbar change [number here] imo. You can put uncommonly used skills on a bar and then add /chotbar change 1/2/3. Like

/ac "Summon" <me>
/chotbar change 1

Put that in set 3. Then when you need to summon something, go to set 3 and press this macro to summon and you'll be sent to set 1 (where your basic attacks are) while you're summoning. Then you can put a 'summon' macro that only contains "/chotbar change 3" in set 1 that sends you to set 3. Basically: press summon macro on set 1 > bar changes to set 3 > pick a summon and cast it> you're now automatically in set 1 again