Do your part. Then get them to keep their promises . If they don't eventually follow through, assume that they have hidden objectives or have misstated their business objectives or were insincere with you. It's OK to drop them and move on. Respect your time.
Sales requires building relationships that are give and take.
Don't be afraid to tell people no. Take the lead in relationship building, but don't invest too much more time in the relationship than your customer does. Ask your customers to do something in return, that when done, shows commitment on their part. If your customer follows through on their promise, invest more time in them and ask for more commitment which leads to a stronger relationship. Treat everyone you encounter as though you are forming a long term relationship with them.