Make sure you are very clear with your vendors, even if you think you are, be clearer than you think. My decorator told us the final price which was hundreds more than initially quoted because what she showed us in our initial meeting was an upgrade. But didn't tell us that, we had the assumption that was included in her package. Nor did she say otherwise. So I just wrote her an email advising of no decoration package upgrades, that wasn't discussed, etc.
Just be clear to avoid last minute frustration when your payments are due. A slight misunderstanding can give you a mild coronary!