I read this and as i was in the middle of cloning something myself i thought i would knock this up I hope it helps
The clone tool can be used several different applications (not just direct cloning).
When using the clone stamp tool you select a sampling point on the area you wish to to apply over another area. By selecting "aligned" in the options bar, you can re-use the most current sampling point...........no matter how many times you stop and start. When you deselect "aligned" you will use thee same sampled pixels each time.
For high detail cloning remember to ZOOM in and make sure you select a suitable brush (airbrushes and basic brushes take care of most cloning jobs)................also, experiment with the opacity and flow settings......you will get the hang of it in no time..................have fun