Pic one seems to be too dark. Try to really get the texture of the plane to show more prominantly. Put some drama into the pic. The top pics usually contain
1) New angle or perspectice
2) lots of action or things to see
3) They don't look like any pic you could find anywhere,anytime in any forum.
MAKE YOUR PICS ORIGINAL....think of some NEW scenario, weather, angle, scenery, combine these elements in an original way. Look at the Gallery pics. What makes them so unique?....If screenart compositions havn't been seen before they'll usually be popular and well received.
Pic #2....see above plus when you show an aircraft close up, try to display it at a realistic flight angle. Your angle in the first pic is more believable. Poorly or unrealistically positioned aircraft can quickly kill a shot. Realism in aircraft attitude is important in creating a shot. There HAS to be some element of realism in the way the aircraft is displayed. Again, look in the Gallery at the angles the aircraft are in. The pitch, roll attitudes etc.....