For every beer/wine/whatever alcohol you drink you consume, drink an equal amount of water - you will be able to have fun till the very end of the party and will not have as terrible of a headache the next day. Also make a habit of having some staples available for a quick meal at all times - some rice, salad and canned tuna will make a quick lunch and you will build a habit of not relying on takeouts all the time.

And don’t forget to have fun! It might feel a bit overwhelming at the moment, but a lot of people around you will be feeling the same way - it will all work out :)