The most important part of selling? No. But without it, a great pitch or demonstration will fizzle out to nothing.
A good salesperson will wrap up a deal as instinctively as he or she might end a conversation with a friend. A poorer colleague would bumble in an inappropriate 'close' at the end to the embarrassment of the customer - we all hate an obvious close. We feel we are being sold something we're not sure we want.
The answer is to not leave the close till the end.
Firstly, you must establish rapport. Listen very carefully to what your customer's problem(s) or needs are and be prepared to question them a couple of times in different ways. People package up what they say so you will not get to the root of their requirements until you do this. This procedure is called 'qualifying' and is something I cover a lot in my emails.
Once you have these facts start to 'tick the boxes'. Offer solutions that fulfill their requirements and when you have agreement, consolidate that part of the sale. (Consolidating is simply confimring with the customer that they are happy so far). It may take one or many small consolidations but you are on your way to getting the customer to bite your hand off!
Of course the customer may well throw up an objection when you try to do this. Great! Customers are there to buy, believe it or not, so if they have serious objections you know they are a serious buyer. If they want to think about it with their spouse/colleague/dog, you know early in the process that they're not.
In taking this 'always closing' approach, you will almost certainly find that the signature can finally be collected with ease because your customer is feeling like they are buying rather than being sold to.