Okay, so I know my way around photoshop (I'm certainly far from exceptional, but I can change a color or two

), and I know all that I need to do to get into my phone. I install themes via ssh on a regular basis, and mix and match themes as well, so I'm good on all that. I also have all of the very useful guides on theming in winterboard bookmarked

.
So my question is, is there anything specific that I need to be able to do with ease in photoshop?
Like I'm talking things that I'll be using over and over again that I need to make sure I'm pretty much mastered on.
And while I'm at it, just another quick question

, when some of the great themer's from this site start a theme where do you start (like icon wise), do you usually start off with the stock icons or what?