Are you talking about piecing or quilting? With piecing (by hand) you should always take a backstitch when starting and this should keep the piece work from falling apart. Many hand piecers also take an occasional backstitch as they progress with the seam. Additionally, most piecework has cross seams which occur when joining the smaller units together into blocks and joining the blocks together to form the quilt. The cross seam also helps to secure your stitches.
With quilting, I always knot my thread and "pop" the knot into the batting.
I don't think you need to worry about your patchwork falling apart. The quilting also helps to reinforce.