I moved my Target Nearist NPC to 'X', just below my movement keys on that side of the keyboard ( ASDF ).
I also use F1-F6 to target Myself/Group Members.
To assist, yes I change my assist key each time.
To help, I use this setup:
/tar <name>
/assist
/g assisting on %g
Once appon a time I used:
/tar <sec Assist>
/tar <prim assist>
/assist
/g assisting on %g
This way I would target the Secondary assist. Then attempt to target the Primary. Then, assist who ever I had targeted.
Now, I just use the one above and flank any secondary assist there might be. If we have multiple assists, it's normally for a single target. Don't need to "assist" for that.