I bought all my weath stuff from ebay- you need a ring, florists wire on a reel, green wire strands and german pins, as well as moss, or you could use an oasis ring but I don't know any tips for that way.
The only thing is that I did my first one using holly and I would say never again. It's harder to work with, as well as being prickly and it doesn't last as long as other greenery though I think you would be ok by now. I much preferred using evergreen, and I found something else with red berries on for colour.
Another idea which might be easier (and save getting the kit) is to do a holly swag, I think they look effective.
I make up lots of little bunches and then wire them onto a wicker ring - this year I will use dried orange slices but sometimes I whole satsumas and rose hips instead of holly berries as we don't have any this year. The greenery is a mix of yew, fir and ivy as that's what we have in the garden. The fir cones come from a tree up the road.