I'm a pretty new user to Photoshop and was wondering if you could help me with the "refine edge" tool. I must be missing something but I make my selection and then click on the Refine Edge button to refine the edge and it's fine. The problem is when I decide I want to refine the edge further, click on the same button and refine it further it shows in the Preview window but the changes are not applied to the current selection. So my question is then am I missing something?, is it even possible to apply another edge refine to an already refined edge?.
You can use refine edge as many times as needed. If find the best way to understand refine edge is to forget about exactly what you want to do with the image you have and just open a new square cut image.
Grab the lasso tool and make a rough selection around anythting in the image. Set everything to zero, and then try a radius of atleast 20 pixels with and then move your slider to contract between -50% and -100%. This contracts your selection between 10 and 20 pixels. Say ok.
Click on the refine edge again, and repeat the entire process to prove to yourself that you can further refine the edge.
The rest should be self explanatory and I hope I hit on the nose what you were having difficulty with.