the simple shadow you placed under the saucer would help the little guys you created, (a little gauss would help) a soft burn brush over the saucer's lower edges could aid in the thickening of the ship (giving it density) (dodging the top accordingly) but then it would become my creation and not yours... the cartoonish effect is done quite well, if you wish to bridge into a more dense image, go for it with my suggestions, but I do love the fact this is recognizable as your own.. GOOD LUCK (and as always.. IMHO)

EDIT: the easiest way I find to manipulate gaussian blur is to go full tilt, open a layer underneath the little ships and draw a very flat oval, fill it with black. Go to Guass blur and just move the slide bar til the edges blur nicely (keep it as dark as it is, you can always reduce opacity later... place the disk under one of the little ships and align it with the size moving it back and forth til it looks good (Use scale to make the size right) then just play with the opacity till it looks well blended (You may have to gently burn the bottom of the ships so it blend well (next time you are driving down the road look at the shadows cars cast on the road, you'll see that it's darker directly under the car and where the wheels meet the road then the rest of the area (that's a guass blur..also the wheels them self will be darker just at the edge where it touches the road (sometimes the exact same color) it's an easy way to create realism.. and to ground and object so it doesn't look pasted on)

Good Luck.. !! and good job

Thanks Drivenslush I just redid look any better ? hey give me all the comments you want Thats how some of us learn Now I have to ask on gaussain blur I always did 3 but now I have it up to 6 was I to low on it plus tried what you said in comment...Thanks

The start pic for the planet surface is a brilliant choice. I would adjust the sky and the ground differently (as the sky result is great while the ground is washed out and kind of flat). The cartoon spaceship and aliens on a realistic background is a valid artistic choice. I think the shadows should be stronger, however, especially where the cartoon elements touch the ground so they don't look like they're floating. The spaceship landing struts should cast shadows plus the underside of the spaceship should be shadowed as well as the aliens' crotches and wheel tops.

Thanks all Here is another redo