Joshua Autumn writes:
In this tutorial, we’ll be going over some quick techniques on simplifying your mesh through polygon reduction, that can really help and improve your workflow when modeling. I will show you a tool that you can use to achieve a quick mesh cleanup in Blender.
We'll be going over the tool of dissolving edges and vertices. In this video, you'll learn what is dissolving, how to use the limited dissolve, how to dissolve edges, vertices, and planes, and why this should only be used situationally.
Update: Joshua discovered a problem with this tutorial and has asked me to remove the video for now. We'll put the updated version here once it becomes available.
As a new learner, it's very useful tips for me...
When Zbrush DynaMesh will come to blender?
Watch the whole video - you might find what you're looking for?
In edit mode, you can also use 'ALT+J' to de-triangulate a mesh which is often helpful. Also, I tend to press 'W' and select 'Remove doubles' too.