I like to use syllables for the drink sizes.
Tall - 1 syllable - 1 shot
Grande - 2 syllables- 2 shots
Venti - 2 syllables- 2 shots
Venti iced - 3 syllables- 3 shots

Hot bar syrup is usually 2/3/4/5/6 (short/tall/grande/venti/venti iced)

Fraps pumps are usually 2/3/4 (tall/grande/venti)

White Mocha/Mocha/Cinnamon Dolce always get whipped cream unless the customer asks otherwise.
If they get an alternative milk, the standard is still whipped cream but I always ask in case they have an allergy.

Ask lots of questions and try to work afternoon shifts if you want any bar time.

If a hot drink gets whip cream, use a size down on the steaming pitcher. So if you need milk for a venti, steam to the grande line. There will be just enough spaces measured out for the whip. Everything else will come with time!

When in doubt don’t be afraid to ask your trainer/shift to write on the expresso machine. And then for cold bar I always check the frap base containers. They show you on there how many pumps each size is supposed to get.