We've helped a handful of software outsourcing firms in the past, however mainly focused on the Enterprise.
What we've found is that software development services is super relationship driven, requires local presence in the communities you target, for the Enterprise it is important to have your credentials in order, is a fairly technical sale (cto to cto) and initially should be about reducing perceived risk then leveraging the customer base to add new customers. Furthermore, it is great to be able to do it all but we believe you'll do even better by positioning yourself in a unique manner and not being everything to all people. This is a very competitive space but ofcourse the need is enormous.
What we would recommend is to:
1. Make a list of your happiest clients and find out why they bought from you
2. Get cases
3. Identify channels and communities similar to "perfect customers" exist
4. Target these emphasizing de-risking
5. Learn, iterate, repeat
Hope this helps.