Sorry! I was out of town over the weekend! I didn't see your post! I honestly can't say that there is a "secret" to clear pictures. There's a lot of factors that go into a nice photograph. The biggest one of course is light, but you already know that! I'd say for mommy and me classes, you honestly would be better off turning on the flash for those. External or on camera, those you want the moments more than a gorgeous photograph right? A fast lens (like the 50 1.8 would help you in those situations, because you can open up a lot more, and raise your ISO, but if there isn't enough light, there isn't enough light and you need to add some artificial light! I really think the biggest thing with getting photographs the way you want them is practice practice. Which I am sure you're sick or hearing, but honestly it's true. I have to be totally honest, I don't do a lot of PP to my pictures. Maybe 3 minutes tops? I fix a few things in ACR (whihc you can be doing int he DPP that came with your camera) and then slight adjustments in PS. But each photograph is different, so what I do in PS is going to be different. sometimes I honestly only do sharpening and maybe a vignette? Sometimes I need to add some contrast or saturate the color more. I do a lot of burning on the backgrounds.
OK, I feel like I rambled and rambled. The overall trick is practice! Don't worry about PS, worry about getting your shots right in camera. Garbage in, Garbage out. PS should be used to enhance, not fix. (though seriously I need it to save me sometimes. You'll get it Betsy, don't be discouraged! Just keep working at it!!