Before going on my exchange I made a questionnaire for my friends to fill out and then seal in an envelope at a dinner party I threw. The idea being that if I was having a bad day I could open an envelope. I wont post any of the filled out forms I received but I will share the blank template and some tips.
Overall it worked out great, watching my friends secretly fill in and decorate their letters was a lot of fun and it also gave me some time to prepare the last course of our meal. Having the happy notes in my bag was also a pleasant reassurance when leaving the country and reading a note could really turn an evening around. The few times I opened an envelope I would pick one at random and usually just looking at the drawings on the envelope would make me smile.
I loved getting a varied mix of responses from both friends I am super close with and those I do not know as well, the combination results in a very surprising mix. I would recommend to bring stickers for your friends to decorate their letters and let them go crazy with them, they make everything more fun. Asking my friends for cooking ideas was super helpful and I recommend it highly for those who are moving out for the first time. If you have notes left unopened save them for the trip home; it'll help pass the time.
You could of course ask your friends to just write you a letter before you leave. Another cute idea is to make happy notes and in secret ask a bunch of friends and family members to fill it out and give the bundle as a gift for someone who is leaving or has a significant birthday coming up. Click here to see the one I made two years ago for some inspiration.