Photoshop is an incredibly powerful tool for image processing. It's made more so by Actions, which record sequences of events and play them back for you — over a whole folder of images if you like. A few things which will help you when recording actions:

Key commands sometimes accomplish functions not in the menus, and are sometimes very useful in action recording. For example, to move the selected layer behind the layer beneath it, you'd normally just drag it. In an action, though, this will name the layers, and will only function on similarly named layers. Instead, use Command/Ctrl-[ or ] to move the currently selected layer up or down. Option/Alt-[ or ] changes which layer you currently have selected, though only through the currently visible layers.

Duplicate Layer is something you do so often that it really should be an action on a function key. Since it's very easy to lose track of which function keys are being used, just include the function key assigned to an image as part of the name: "duplicate layer F6". I also have New Layer and New Layer behind on Fkeys. You might want "Save As Web..." on an Fkey if you're doing it a lot. Whatever works for you.

Fills. Shift-Delete/Backspace to access the fills dialog, which fills the selection, or the whole current layer, with a number of options. Often used with the Preserve Transparency checkbox. Shortcuts for the most common fills: Option/Alt-Delete to fill with foreground colour, Command/Ctrl-Delete to fill with background colour, add shift to either of those to Preserve Transparency of the current layer. All good.