^That, and make sure you get a MyDevice and the eletronics keys (to open the security "locks") from the person going on break. If you can't get a MyDevice then it's gonna be pretty difficult to help customers (both irl and phone calls... especially as a newbie).
I always look up on the MyDevice what the customer is asking for. If I'm dealing with them irl I say something like "I'm sorry, I have to look it up, I'm new" or on the phone I say "can I put you on hold for a second while I look up the item(/look for the item)?"
A tip, maybe you already know, but you can use the merch locate button and price inquiry on the cash register (but you need the DPCI).
Do reshop/gobacks, it's a good way to learn where everything is.
You don't have to know everything so don't stress out about it (no one can know everything, anyway).
If the customer asks for a TV or something that you can't find, just call for an LOD or call for help (or someone you know that's nice/helpful and on the floor)... or look for any TM near you.
If a customer asks you to open up an item that costs more than $50 (or it might be $100, I'm not too sure, but let's say $50 to be safe 😛) to see the stuff inside... you need to call the LOD and have them open it.
Also, when a customer asks me about anything regarding phones I just direct them to the Target Mobile person. If they're not there (since they're hours are short), I do try to help, but you can only help so much, especially if they're asking about plans.
For the guest calls, 99.9% chance that they're just asking about items in the store ("how many of ____ do you have left?" "do you have ____? can you hold it for me?" so having a MyDevice is incredibly handy. It's really hard for me to help them without a MyDevice.
This may be ASANTS, but my store let's TMs use their own smartphones to look up items (in the Target app). It sucks because it doesn't show the shelf location, but it does show the aisle # and DPCI.