Not surprisingly, the techniques for ending the thread resemble those for starting the thread.
And now for a strong suggestion--do not knot the thread. An exception might be made for a special case, such as an isolated stitch with no other stitches near it in the design.
One good method is to run the thread under four or five of the stitches on the back. You may choose to whip stitch around one of the stitches as you are running under. This helps to lock the thread in.
Sometimes dark colors show through when woven under lighter colors. Check to make sure this isn't happening.
If you stitch in a manner that leaves vertical lines on the back, try whip stitching or weaving up (or down) a few of these vertical stitches. This technique makes for a very neat looking back.