I am busy at present writing bits and pieces for my 'Welsh Landscape Art' course. So, to keep things moving I would suggest that if you haven't done so yet, that you read these two books. They are very special. Even though I have been painting for quite a few years these books have caused me to almost start again. They will tighten you thinking, give you wonderful advice. Between them they will offer different points to begin from, one very much indoors (plus landscape), the other very much outdoor (plus still life). I could ramble on ... but you need to get your hands on them yourself and slowly soak them up.
Sorry - you can't look inside the lower one unless you go on Amazon, then you can in fact look inside both books.