How do I remove vertices within each other?

I’m just starting out on modeling and it seems when ever I extrude I get an extra set of vertices overlapping each other. Is there a way not to have this happen?

As easy as it is, also it is not. However it can be a lot easier than it is at first. That being said, there is an extra level of consideration and care that must go into it that is, only upon extrusion, immediately apparent. Personally I have only reduced the extra geometry by taking extra care about how I handle it. Such as not doing a bunch in succession and checking for extra geometry as I go. Use Circle-Select on a vertex and if it shows more than one selected then there is extra geometry. Cleaning…

In my opinion, merging all that extra geometry is not the way. As easy as extruding is, also it is not. However it can be a lot easier than it is at first. That being said, there is an extra level of consideration and care that must go into it that is, only upon extrusion, immediately apparent. Personally I have only reduced the extra geometry by taking extra care about how I handle it. Such as not doing a bunch in succession and checking for extra geometry as I go. Use Circle-Select on a vertex and if it shows more than one selected then there is extra geometry. Cleaning… sometimes it is easier to delete that piece and start with a fresh face.

As easy as extruding is, also it is not. However it can be a lot easier than it is at first. That being said, there is an extra level of consideration and care that must go into it that is, only upon extrusion, immediately apparent. Personally I have only reduced the extra geometry by taking extra care about how I handle it. Such as not doing a bunch in succession and checking for extra geometry as I go. Use Circle-Select on a vertex and if it shows more than one selected then there is extra geometry. Cleaning… sometimes it is easier to delete that piece and start with a fresh face.

I get this if I let go, right click, after extruding. The new edges return to their start point as double verts. I usually use the 3d cursor to move them in X,Y Or Z from there. The trick is to only press E once.
You could turn on merge verts to automatically merge them after, or select them all then press W, R to remove doubles.

Select all, W -> remove doubles.