I want to throw a house party but...?!

I am a little worried. I am 16 years old and i want to throw a house party purely for fun. I already talked to my mom about it and she is fine with it. There will probly be drinking going on. So im wondering what my risks are. I will be inviting around 20 people in my grade (11). So i wondering like what the risk is for cops coming?. I plan on cleaning up beforehand and moving anything expensive/breakable out of plain sight, Also i will be locking all of the bedrooms cause i dont want people doin they thing in my room lol. But anyways if any one wants to give me some party throwin tips or their experiences that would be great. Also i wont be supplying alcohol but i will be allowing ppl to bring it if thats relavent.