1. There is alcohol and drugs at a party and you do not want to consume alcohol or use drugs.
2. You could avoid the areas/people consuming alcohol and/or using drugs. You could hang out with people at the party that are not using alcohol or drugs. Walk away from the situation if someone offers you drugs/alcohol by using excuses like "sorry, I need to go find ....... right now" or "I've been taking medication so I can't." Being assertive is another option - you can tell them directly and confidently that you don't want to take drugs/alcohol.
3. Avoiding certain people could result in conflict if they notice you are purposefully avoiding them. Making excuses with dishonesty could get you in trouble if someone catches you in a lie and they could approach you later on and ask again. Being assertive can make them have a negative view of you.
4. Think about what would be safest for you and those around you. Being assertive would work most quickly and effectively. Tell the person directly but politely that you can't take drugs or consume alcohol. If you can provide an honest reason e.g. "parents won't let me" or "my parents are picking me up and I'd rather not risk it", then that'd be better.
5. After evaluation, it's possible some may disagree with your decision but your goal was to have a safe, fun and sober night out - this goal was achieved.
note: just guessing here because i'm not 100% certain but I hope it helps!
