Well thats a though call, clients always want more but here are a few point you should consider:

HTML Mock-ups: Always create HTML mock ups to define the UI part of an application, show them how will it look like and ask them for their opinions. If you find anything reasonable to change make it happen in the HTML prototype. Using this you will sort out lots of things like UI issues, basic flow and some add ons(like Sorting, Pagination, no. of records to be displayed etc.)

**Active Participation from the other end:** This is very important if you are developing for a business organisation, get in their business ask them to clarify your doubts and without fail ask them what changes do they want in their flow (if required).
**Modular release:** Release your code in a modular fashion, release, test, take feedback and release again.