Tools and processes when creating custom themes

Hi all,

I’ve been working with ready themes for quite a while. Now I am planning to work with own custom themes. I’d be interested to hear your comments about what tools/programs/plugins and processes you have found as the best way that works for you? For example how do you create the basic layout, is there any good tools to work with css etc? I have checked out many tutorials and they all seem to have their own approaches so it would be nice to hear how people work themselves / what is the most efficient way that has worked for you.

My biggest difficulty is the css which I am not very good at. So any tips (essential tutorials / programs etc) for working with it would be appreciated.