1.) Internal means inside. For example; it could be the feeling of wanting to be cool, or stand out in a crowd of friends. Not wanting to stand up for yourself if faced with peer pressure, because the fear of being rejected/shamed. A good one would probably be having a low self-esteem, depression, not caring about health or caring to think about consequences.
2.) An easy one would be seeing important people in your life do drugs, parents/family, close friends for an extended period of time. Being exposed to cigarettes by second hand smoke could also make you feel like it's okay to smoke firsthand.
3.)Umm, you could practice reminding yourself the health risks/longterm effects of doing drugs. Striving to be the best version of yourself possible.
External means outside, so basically how people could influence you. Remind yourself to always say no in case something peer pressure-like pops up. Explain that you respect the others choices, but you have your own choice and opinion, and you hope there's no hard feelings. This could be a way to avoid further peer pressuring, or feelings of shame.
Step-by-step explanation:
This shouldn't be too hard, especially since the answers should be based off of your opinions pretty much.