I used vintage wallpaper, a piece of quality card and some vintage lace. Fold the card in half then cut out two hearts, stick the lace down with glue.
Glue down one on the hearts on top of the lace, then sew (machine or hand sew) the other directly on top.
And that's how easy it is! I think it looks cute and not to fussy, sometimes wedding cards can be over the top!
I also made a quick envelope by sewing two pieces of card together then gluing down some lace and sewing a single heart on top.