1. Trying to enlarge a small image but ending up with a lot of stretched pixels?
With the image layer selected go to Image> Image size and change resampling to Preserve Details. Now increase the size.
2. How to cut-out messy hair in photoshop.
Select your subject using object selection tool> Add mask and duplicate layer> Select mask and go to mask properties click on select and mask> Paint all over the hair and press enter.
3. How to change body position on photoshop.
Go to properties tab> Click select subject > Go to layers tab and duplicate the layer> Hold ctrl. And click on layer icon to create a selection > Go to select, then modify and click expand> Select pixels at 10 and click ok > Go back and select first layer > Right click on selection > Click fill , make sure the content is set on content aware > Go to edit > Select Puppet Wrap > Now all you have to do is adjust the body using different points