Basically, there are 2 approaches:
1. Concatenate both facts into 1 fact table and connect all dimentions to it.
This is also called Star Schema and it's the most common and simple to apply.
2. Key Table - all facts and dimentions are linked to 1 Key table.
The pros and cons are explained very well in QlikView free training service (http://www.qlik.com/us/services/training) The training is called: Technical Pathway - Qlikview 10 Modeling Best Practices (7/8/2011)
Also, you may find a good PDF that explains it.
All the best,