What to wear?
Wear whatever makes you happy, pick colors that cheer you up.
Check that your cloth is niether too tight (so you can breath and move naturally) nor too loose and your pants are not too long so you don't trip over them.
It's worth it to invest in a high quality maximum support sports bra, especially if you are more then B cup.
Bring water and a towel with you.
Should I drink water during the class?
Water Tips for Efficient Exercise.
Your ability to perform athletically can decline with a very small amount of dehydration. Drinking water during exercise is essential if you want to get the most out of your workout and feel good while you’re doing it. When you’re working out, you’re more likely to be losing water, both through your breath and through sweat.
So how much water should you drink before, during, and after a workout?
Drink 0.5 liter of water one to two hours before your workout,
drink one more glass of water 15 minutes before you begin,
drink 150-200ml of water every 15 minutes of your workout.