Photographing children and pets is always challenging. Try carrying a whistle or other attention getting device to stop (or slow) the action.
Make sure your horizon is horizontal! There's nothing worse than looking at a breathtaking shot with a horizon tilting to one side. Tripods with built-in levels are very handy for crucial shots.
Whenever possible, keep the light source behind you and falling on the FACE of your subject. Use sidelighting to emphasize depth, dimension or texture or backlighting to emphasize shape, form or drama.
Search Yahoo! for the latest photography news
Yahoo! Industry Center - Photographic Equipment & Supplies