Before you give your presentation, find out if you're talking to the Decision Maker (the "DM").
Failure to do this results in serious disappointment when you find out that the person you've been pitching to has no authority to make a decision.
But rather than simply asking: "Are you the DM?"
Ask a better question:
"How do you normally make a decision like this?"
"Who else is involved in the decision process besides yourself?"
"Walk me through your decision process."
"Other than price, what factors are important in this decision?"
These questions should focus on the "Three P's"
People (who is involved)
Process (how are decisions made)
Priorities (what criteria are used to make this decision)
Don't be afraid to ask these types of questions.
If you get good at this you will save yourself so much time and frustration.
Good luck!