First Day

Monday will be my first day as a union apprentice pipe fitter. I previously worked as a metal fabricator/welder for almost 2 years, but that was almost 4 years ago at this point. The past two years I have worked in a warehouse doing nights but finally got my opportunity and was already given a contract that should last at least till the end of the year.
I’m looking for any tips or tricks so I don’t look like a complete dumbass on my first day. I would say I’m green as can be when it comes to pipe fitting so anything’s appreciated, thanks!