ive had my theme up a while back.
but ive just recently started to thoroughly make the theme.
photoshop is a good start.
so when you edit the icons and stuff
second thing youll need is an extractor for .zip files.
winrar and win7 are both great.
i switched to win7 and i feel happier but its all up to you.
then youll also have to get notepad ++ if you want to edit the updater script (the thing that makes the text pop up during installation/flashing)
and youll need an imagination.
to create icons or think up of stuff to change.
you can extract the files from .apk like if they were zip files.
once you edit them you can just simply drag and drop them back from where you got them.
if you have more questions you can ask. i know that sometimes im not very good at explaining things.