I think postcrossing is a very cool, and very human project, so here I am, participating. I really like the idea of connecting people and helping us sharing our part of the world to each other.
When it comes to what postcard to send I'm not picky. I suggest that you pick a card that you like, for what reason it may be.
For 2021 I actually have a special request. If you have any medical themed cards (nurses, doctors, medication, medical equipment, anatomy charts e.t.c.) laying around, send me one of those! And if you're from Finland and don't know where to send Inge Löök cards, well send me one ;). I also collect "Keep calm" card.
If you don't know what to write you could always tell me why you chose that particular card or put down something about yourself. I also think it would be fun to know a proverb or saying in your language (with translation...)
Have fun postcrossing!