Alas, I know of no dedicated resource on how to debug a website w/ Mini, though there are a few related articles on http://dev.opera.com that might help you. The most recent article is A developer's look at Opera Mini 5, but Making Small Devices Look Great and Designing With Opera Mini in Mind should be particularly useful as well.
Generally check how a site looks in Opera Desktop and use Opera Dragonfly for debugging. Another good tool for debugging is MicroEmulator when used w/ a locally downloaded version of Opera Mini and a resizable skin.
Also, there is a special url in Mini that allows you to access the ECMAScript error console: just type "debug:console" in the url field. You can combine this with calls to opera.postError() in the development version of your site to post any string to that console. However, it won't show you html tags.
I could probably help you better if you had a more specific question.
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
