That is the #! question asked and it so varies from person to person, company to company.
What is your experience?
what services are you bringing to the table that would provide you a niche?
What have you done so far in regards to marketing.. flyers, brochure, postcards, resume, website..etc etc
4 demo's really only says to me your selling software. WHAT services are you selling? Software is a crap business right now.. plenty to go around. No offense.. just telling it like it is. You need to have services and a reputation/resume to stand up for your business. It is a tough market and you need to know all there is which is a heck of a lot more than software or demo's.