This was a question on Quora - and my answer for it.
Get In Their Billing System
An old manager of mine once laid down the law. Business relationships don't start until someone signs a check. You don't have a client until they're paying you, and if you're selling large deals, that check is going to take longer to get signed.
If you're working with a large enterprise, you need to figure out how they bill, and get them in the habit of working with you. Nothing works better than setting up a monthly billing arrangement that gives them a taste of what you offer. This doesn't mean you discount your prices or sell them your best product. Once you discount a product or service, it's very hard to get it's price back up to par. It does mean that you should have something that you can sell them that your contact has the budget to approve.
There is a lot of value in this. You're listed as a supplier for the company. You're getting a check, however small. When it does come time to bill, your company is already in the system. The manager/executive has a comfort level of working with you. And they have a reason to speak with you other than you calling to ask if they are ready with that order yet.
**if you're not comfortable selling a small piece to the executive that you're selling the big service to, consider finding another manager to sell a smaller service to. You're still in the system.
Stay In Front Of Them
If you've made the pitch, and are waiting on feedback, now is the time to kick in your PR/Social Strategy. You've identified all the people who are needed to sign off. Now go stalk them. Create a mini-calendar of content that addresses topics they would have an interest in, and get those out on Twitter, LinkedIn, emails, blogs, press releases, and videos. You can't forward everything to the person, but that's not your goal. Your goal is for them to stumble upon you (no pun intended). If they see you three or four times a month on social or in trade magazines, they're more likely to feel comfortable with you, and more likely to take you from the Red Zone to the End Zone. Show up at their events, and don't bug them. Find ways to get your company in front of their company (small, sponsored events). LinkedIn, Meetup, Eventbrite, Facebook - all of these hold clues for you to get your name and brand in front of your prospect.
That's the point of social. You're telling them non-verbally, that you are someone they should know.
Make It Personal
One thing I learned as a salesperson is that my company isn't doing anything for the client. No matter the product or service, my company isn't fixing theirs. I'm selling my product to an individual, whose career I will help if it goes well. When selling to enterprise clients, try to understand what that exec/manager needs to improve their career, and don't forget to sell that benefit to them.
If they can put something on a resume, improve their visibility to senior management, add money to their budget, or have a case study they can brag about, they are more likely to buy from you. If they are just going through the motions, they're not going to see the value for them. And that's when they start dragging their feet.