As with most other home improvement projects, coating your concrete floor requires some serious work and research. If you go into it without any of the necessary knowledge, chances are your floor is going to look worse 
than it did before you got your hands on it. There are several very important things you must know and do before you can even think about coating your concrete.
First, you need to evaluate the surface of your concrete. It must be clean and not contaminated with other foreign substances, such as concrete curing compounds, oil deposits, old paint or any other material that would interfere with a proper coating bond. Also check it for unevenness and density. Preparing the surface is the single most important step in the coating process and if it is done improperly, it will severely hinder its long-term performance. Different surfaces also require different prep work. There is so much to know about surface evaluation, which is just one step in the process, that it is often a better idea just to hire a professional to do the job. Bach Custom Coatings is a Portland, Oregon based company that specializes in installing epoxy garage floor coatings as well as industrial concrete coatings.
Yes, hiring a professional is probably more expensive than doing it yourself, but it is probably not worth the savings when you discover several months down the road that you didn’t do the job right. There are a surprising amount of complex elements involved in concrete coating. It seems like a simple job on paper, but the fact of the matter is that most people who decide to do-it-themselves often find out the hard way that they have no idea what they are doing.