Tips on Animation

Hi guys! So Iv'e been doing Lego stop-motions for over a year now, but I feel like they are all lacking......something. I'm not sure what it is, but something is not right, and I'm not content with my videos. Do you guys have any tips of what makes a Lego stop motion so great? I have a pretty good camera that takes clear, nice pictures, and I believe my animation is pretty decent too. I think I may be lacking in the sound/audio effects department, however don't restrict your tips to just one category. Thanks!