For you’re first 2 attempts I’d be pretty happy if I were you though i would definitely play about with oil glazes rather than acrylic. Personally I’m all about oil glazes for faux marbling as I think they offer distinct advantages to water based alternatives - first and foremost you have have a much better ‘open time’ with oil glazes so you can play around with the paint and manipulate the glazes to get just the finish you want.
If you set yourself up with a few tinted glazes, a hog hair brush, a good quality badger hair softener, a couple of Canadian goose feathers, a long haired sable brush (for the veining) and a lint free cloth for playing about with the background then you’re well well armed. Just have a play and see what effects you can create, it’s all about experimentation. It’s taken me 13+ years of ‘playing’ about to get my process down and I’m always tinkering.
Veining wise, i think less is more with a lot of faux finishes, after all every piece of marble is naturally different. Below is a bit of a guide to good and bad veining, the picture shows what not to do - hope it helps.
Bad veining - although really oversimplified common faults are: parallel lines, wobbly veins, cobweb effect and lines that are broken.
Good veining - although the vein may split at intervals to form quite complicated patterns, two veins of the same tone should never cross.
All the best with the experimentation, I look forward to seeing the results!
If you want to have a look at some of my faux marble check out