These effects are great for transforming a block, concrete or a flat wall into something very elegant and beautiful and they are easy to master using a small investment and a little practice.
What I recommend is that you buy the proper coloring agent for the product that you are using and pre-color it before you apply, so that nicks, bruises and scratches will never stand out. I also do not recommend using joint compound. Because joint compound tends to dry unevenly and cracks appear throughout it if your coating is more than 1/8th inch thick, unless you want the cracks.
Some products require a coat of Weld-bond to be applied over sheetrock or painted surfaces. You should ask sales agent exactly what the proper method of prep is involved or it might just peel itself off while drying. Also you don't have to do a professional repair job, but you will need to tape and repair cracks around doors and windows using mesh tape or even patches sometimes. If not then they will crack through the finish almo0st immediately.
The other thing I recommend is just mix about 3/4 gallon of product and play with it first in a test area. You can usually use it a few times, just try it out, look at the results and then scrape it off and try it again and then again to get the feel of the product. Once satisfied go crazy and get to it. You'll be saving yourself several thousands of dollars and increasing the value of your property by a huge amount. If you're like me you might even have a good time doing it too.