A referral is very helpful. That's not always easy but it's worth racking your brain to try and find a connection.
It's also worth aiming as high in the organization as possible. In large companies most people don't have the authority to purchase anything of significance.
It's not just an issue of money. If buying your product changes the way they do business in any meaningful way then some authority will be required to approve those changes. Does the person you're talking to have that authority?
It's much easier to start high and then have that person push you down to someone lower in the org to do the leg work than to find out after months of effort that the person doesn't have the authority to consummate the purchase. If VP X tells manager Y to look into something at least you know VP X thinks it's worth the time.
This implies that you need to craft your value proposition and benefits in a way that is appealing to someone further up the food chain.
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