Old Advice

I think the biggest mistake that I see amatuer writers make is not conforming to the age old saying:

Show, Don't Tell. The thing I hate most is when I see people use "You see, Daniel had special powers..." If the whole book is about Daniel's special powers, you have to show them, possibly by having David do it himself.

Let's say Daniel had the power to rewind time temporarily.

"Daniel walked down the cafeteria, looking for an empty seat, the sloppy joe jiggling on his tray with energy. He noticed he was walking towards the 8th grade "section" of the cafeteria, and quickly changed course.
A little too fast. His feet slipped underneath him on the wet and milky cafeteria floor. His tray flew upwards, going in a large arch towards the 8th graders.

Daniel watched in horror as the sloppy joe smeared into the face of a beefy 8th grader. The entire school froze as the boy wiped the BBQ off of his face. He started to stomp towards Daniel, who was still transfixed. He grabbed his shirt, yanking him off the floor.

Daniel snapped to focus. He felt his energy dissapear, and the world start to rewind. The boy set him down, and marched backwards. Daniel himself moved positions as the sloppy joe flew back to him. He looked at the 8th grader, doing their same conversations, and walked towards the 6th graders.

What's better?

The above example or, "You see, Daniel had the power to rewind time..." I really hope you think the 1st one.

So, try to use the Old Advice

Show, Don't Tell