more advice, focus on one body part at a time, start with your legs then work your way up. Don't move on till it feels good. You want to look for stuttering which means you have an unnecessary frame somewhere (which you do in this animation). make things gradually move back and forth.
I just removed some neccessary frames - mostly where the legs didn't change their position much at all so they didn't warrant a new frame. Coincidentally it fixed the stuttering on your gun. Which makes me think you added frames just to stretch it out. You're using graphics gale? Play around with frame rates in each frame option, rather than add more frames - add frames if you need to. if you can achieve a smoother looking animation cycle with less frames is better than more frames and a stuttering animation.
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it would also help if you put these gifs in img tags, numbering each frame, and also have it spreadout frame by frame. You'll get more people who can offer you case by case advice if you moved this to workshop.
edit:
like I said you don't need a detailed model, just use blocks and rectangular geometry. for side scroller put the camera facing straight on the model, for top down, have it above and rotated 45 degrees.