None of the following is meant to offend or attack anyone, it's just hopefully getting you to think and understand the business climate of larger companies.
I have sold my own company's services into many Fortune 500 Companies including 3M, Target, Samsung, Intel, Google, Microsoft, Amazon and a lot of other publicly listed companies you may not have ever heard of.
I have also worked for a Fortune 5 (UHG) as an EIR, and have sold semiconductor components into another whole slew of companies.
Don't think of large companies as, "large companies." Think of them as many different medium sized companies stitched together.
Don't think of these medium sized companies as abstract groups, but real individual people who are trying to achieve real business problems, and potentially having a lot of internal factors to keep their projects afloat. While these medium sized companies may be well-capitalized in terms of their continued existence, they are continuously tasked with reporting and demonstrating business value, meaning there are some kinds of Key Performance Indicators (KPIs) which they have to follow and demonstrate and report up the chain.
Understanding the context of the company and what division they are in and what that division does and how it fits into the overall annual report (if they are a public company) is extremely important.
Basically, if you start off with, "hey, I'm building a service, I want to talk with you." That is already getting you off on a bad foot. Rather, you need to have a compelling reason that they would want to talk to you, that solves their problem, ahead of time. That's kind of a Catch-22, since you have not talked with them yet, so you basically have to do research and network with others who you know connected to that company to gain a better understanding.
The process of enterprise sales is also extremely long - count on possibly two years, depending upon what it is. Beyond that, if you're in the process of developing something new, you may need additional time on top of that.
If you're developing an interesting startup, you might consider applying to speak or demo at a conference which you know to be at least fairly high quality as a way to network. You basically have to constantly network and find real people, and understand what role they are in, and how their role fits into the overall environment, and then from there work on figuring out what their problems are.
You should develop a list of common problems and build out a questionnaire where you ask what are the main sources of concern for achieving their KPIs. Are they having more difficulty with a particular problem-solution set in relation to human resources, awareness, getting guests in the door, working with some kind of database, or something else? Where are their main concerns? Is what you are developing even touching on anything that they are hoping to achieve?
Beyond this, you should of course be developing a lot of competitive information on what else is used in the marketplace already to solve the, "problem areas," that you are working on, and be able to share that information with them. Essentially you want to be a sort of, "free consultant," for them, and you want them to feel good about meeting with you. You want them to know that you care and have a relevant set of knowledge that is possibly going to help them move forward.
Over time, you will want to build and prove out trust. You don't want to build trust as in, "just trust me bro," but a real report card of grades that they would give you which speaks to not to how chummy and friendly you are, but how relevant your potential solutions are to solve their problems and keep them gainfully employed.
Beyond this, there are frameworks that you should be able to adopt over time to help you identify different parts of these teams of people, and how the different parts work together and relate to moving a deal forward and being able to close it. There are a lot of different enterprise sales frameworks out there, one that I would recommend is, Strategic Selling.
Essentially, you want to be able to adopt a plan to map out how different individuals may relate to the information you are trying to get. If you are building something, then I would think that eventually some day you will want to sell it, so being able to come up with some kind of framework for gathering your marketing information that allows you to hopefully close a deal which turns into a signed contract is essential.
Start with Miller-Heiman http://www.amazon.com/New-Strategic-Selling-Successful-Companies/dp/044669519X/ref=sr_1_5?ie=UTF8&qid=1464613332&sr=8-5&keywords=solution+selling
Then up your game with the Challenger Sale http://www.amazon.com/Challenger-Sale-Control-Customer-Conversation/dp/1591844355/ref=sr_1_1?s=books&ie=UTF8&qid=1464613441&sr=1-1&keywords=challenger+sale