Well, you have the idea of placing your shadow detail on, or about, zone III down pat. The next part of the equation is to decide how long to develop for. This is complicated by the fact that you do not currently do your own printing. To obtain your standard dev time you really need to find the time it takes to get your zone VII tone at the level you want on the paper at the same time as when your zone III is where you want it on the paper...

I would second the idea of taking a course if you find it a pain to plough through a book. I have seen some web based descriptions, but they were too simplistic or, in one case, far too complex - I gave up myself after the 15th page or so... Other than courses, only books seem to be the answer.

There is a rule of thumb that often gives immediate improvement: cut the ASA rating of your film by 50% (e.g. rate 400ASA film down to 200ASA) and reduce the manufacturer's recommended development time by 15%. This biases your shots towards the old "expose for the shadows, develop for the highlights" mantra. In really bright, contrasty light, cut dev by another 15% and in dull, overcast light, use the manufacturer's recommended time. For example, testing FP4+ gave me 80ASA and a standard dev time 10% less than Ilford's recommended time for ID-11 1+1. Had I just used the suggestion above, the difference would be hardly detectable and would have saved me 3 rolls of film and the couple of hours it took to do the testing...

Barry Thornton used to have some articles on his site that explained a simplified zone system but since his untimely death the site has gone away (available however in the web archive at: http://web.archive.org/web/200312290...hornton.co.uk/) I converted the articles to PDFs but I'm not sure I can upload them here due to copyright restrictions.

Have fun, Bob.