I generally keep the tasks similar each month; but anything that involves the tcg would be fine;


Ask for certain cards (magical girls, animals, heroes, swordsmen)
Level/gain so many cards
answer so many games
trade with so many players
turn in so many sketchpads
gift other players
use art shop/art studio so many times/max out
grab from RA (wouldn't recommend this since ra is tiny);
fanart/fanfic (this is purely by your choice! I like it because i love having more art/fics of the colors universe! and its a chance to get more cards for bonus)

How you arrange it and set up the tasks is up to you~ I would recommend not having more than 2 asking for cards tho.

Fel says we don't really need anymore graphic donations.

And for Level up task, if you've noticed I started to do a card cap instead. Because lower level players can easily level up, but players in upper precious, flowers and planets it's really hard to level up in 1 month unless they're really close;

as for prizes, usually I have two separate prizes so players can choose. the only time i keep it to one prize is for big things like extra release slots or 2 cards per crayon

but some ideas
extra deck donation
special deck donation
lowered art studio rates
Extra cards (ten or so?)
5 choice chara cards / crayons
extra cards for games/sketchpads/levelups

:) Sorry if i rambled a bit! If you have any questions ask away~