For those who have done the brush embroidery...what did you use for a pattern? Did you imprint the cake first, just wing it from a picture or what you had in your head, or trace it on the cake?

Also did you use royal icing or buttercream? I've only made royal icing once and its pretty gross if you ask me, is there something better or a way to make it taste better?

I am wanting to make a cake for my in-laws 40th anniversary. Thanks for any help you can give me!

It depends on what look your going for. You can use a cookie cutter or do freeform piping and take it from there. If you are covering in fondant it will be easier to wipe off if you don't like it.
A crusting buttercream works just as well. I have added flavoring to royal icing and it tastes much better.

I used buttercream on buttercream no problem at all. For me the trick was only doing a couple petals at a time and make sure you dip your brush in water then lightly dab on a paper towel for each new petal. As far as the form, I was doing a cake with hydrangeas so I used my hydrangea cutters as my guideline and traced that. Turned out great! It's in my pics if you want to see it. It was my first time doing brush embroidery and am very happy with how it turned out and how easy it was.