What I like to do and seems to come out the best is using Mudbox or another program like it to generate normal maps. I take my low poly version of my model to Mudbox and make it really high poly, so I can sculpt all the details in that I want the normal map use. Then you can generate a normal map from the high poly version and apply it to the low poly version. Doing it this way gives you a lot of freedom with how you want the normal maps to look. The only problem is that you will have to learn the program and you might not have the time for that.