Dmc Cross Stitching

question about cross stitching?
I was just wondering how much thread you guys use on one pattern? The pattern that I am doing now is DMC 117. I think DMC means type of thread. I am using 4 strands of the thread, but the thread is thin. I am almost done with the cross stitch, but there seems to be gaps between my cross stitching. I don’t think I am doing it too hard. Please help! What am I doing wrong?
http://www.cross-stitch-centre.co.uk/acatalog/tutorial.html
http://crossstitch.about.com/od/learntocrossstitch/u/crossstitchbasics.htm#s1
These are a couple of links for beginning cross stitchers.
I usually use two strands of thread for the cross stitching. The chart directions usually specify how many to use.
Then sometimes the pattern will have a half crosstitch and leave a gap. Sometimes patterns will call for outlining things with one strand of thread. That technique will bring stitches together.
DMC is the brand of thread.