Sure, with most of my extractions I use a mask applied to the layer and then brush away the edges around the item on the mask part of the layer, that way if I make a mistake I can brush bits back in.
I always drag my image onto a large high resolution canvas, say 12inches square and 3000 pixels per inch. Then I reduce the pixels per inch to 300ppi before saving it when I am done.
Working on a 12 inch page ensures I get the size I want too.
I find that using a small soft brush set to minimum spacing avoids getting those pesky jaggies around the edges of the element.
hope that helps