Photoshop Tip for beginners
 

After you remove a model from her background, you often have to scale a model down to fit your composition. This often leaves her looking blurry ... there are a couple of things you can do to avoid this. First of all, when possible always scale down in even percentages. 20%, 25%, 50%.

After scaling her down, use your sharpen filter (FILTER>SHARPEN>SHARPEN) ... but WAIT! This is a no-brainer, but the trick is to FIRST select the model by CTRL-Clicking on her layer. Then go to SELECT>MODIFY>CONTRACT. Contract your selection by 1 pixel. NOW sharpen your model. Doing this will help you avoid those "blocky" edges also known as stairstepping.

Stairstepping is a big pet-peeve of mine ... I hope this helps.

The unsharpen mask followed by a sharpen also works very well suprisingly