You could print out the invitations in colour.....or colour the black and white versions yourself or get the kids to colour them in before giving them to their friends!
You could make actual cards and put the invitations inside as inserts.
We have digi versions of 'Halloween Josh & Jodie' in colour and blackline to decorate the front of the cards.
I have also added sentiments with coloured backgrounds in the party invitations pack so you can cut them out with your Nesties.
There is also a blackline version of the sentiment without a background so you can print it on top of the papers if you wish.....or just onto a white background