My thoughts on this card: Keep all the sentiments you get, I don't use this sentiment from Penny Black too often, but when I do it is the perfect wedding sentiment!
Keep practicing! and cut/crop your paintings to make your paintings work for you! I paint on a daily basis, sometimes I love them enough to frame them or keep them, but most times the warm-ups I create are not anything I am going to keep, so I use them for my cards!
I challenge you to cut up and crop your warm-ups or your studies, you will feel joy when you can create a card to send! I like to think of it as Creativity is meant to be shared!