Some good advice when making icons from layers in Photoshop:
Always remember to name individual layers. It can get easy to lose track of what is what if you don’t label each layer accordingly.
If you don’t already have the checkerboard pattern turned on in layers, turn it on. It is much easier to spot semi-transparent pixels against the checkerboard pattern than against the white of the background layer.
Experiment with the opacity settings of a layer to help achieve the proper settings for masking.
When editing icons in Photoshop, it’s handy to zoom in on your open window to 400-800%. Once you’ve done this, use the View—> New View command to open a separate window that stays at 100% to see how the icon looks at actual size as you edit it.
Once you’ve completed your individual icons, place them on the proper grid file for construction in IconBuilder. Getting into the habit of using preset grids early will save time and effort later on.