Well you're actually responding, so that means you're on the right track! lol
Go to the lane you're directed to, and stay on until the GSA/TL sends you back or it's absolutely clear you're no longer needed.
1) Empower yourself to make it right for the guest. If a price change (or anything) doesn't require a supervisor number, don't ask. Just change it.
2) We aren't the coupon police. We more-or-less take every coupon handed to us. If it doesn't accept it, make a quick glance and if it looks reasonable just accept it.
3) You're the final impression the guest gets of Target, so provide great service and make sure they leave happy. If your guests are happy, your GSTL will be happy.
4) Don't be afraid to use big bags for towels and bulky items.
5) If it's a transaction full of clothes, take all the hangers off before you start ringing. Makes things go quicker.
6) If you have a quick/small question that you don't know the answer to, odds are your checklane neighbor does. Ask the cashier next to you if you think/know it'll be a quick answer. It saves both you and the guest time.
Last: Have fun with it. Nobody LOVES backup cashiering, but it's part of your job and your LOD will understand if you're stuck up there. So instead of dragging ass to the front lanes thinking "ugh i don't want to be here, i don't want to do this, this sucks and isn't my job, i have too much other crap to do today, lets get this over with" that'll come across to the guest and it won't be a good experience for either of you.