Unfortunately, I can't give you any specific tips because I don't know what you're trying. Developing software appliances can be very tricky if you're doing it for the first time. There are many ways to skin a cat. We'd like to work on a custom appliance extension mechanism that is simple to use but we haven't gotten around to it yet. There's just so much to do and so little time to do it.

For now the best tip I can give you is to carefully document what you are trying and the results you are getting in the development wiki.

It would then be much easier for me (and others) to take a look and give you some guidance.