The main pushback we see is the following: 1) It is hard to get budget carved out for new enterprise software without explicitly showing saved time, saved money or more money. The best bet is to find a "champion" will will work with you to build out case studies and sell internally. The issue for that person though is they are going out on a limb and that is a double edged sword.
2) We were selling software to someone that essentially did the same job as our software. It created a lot of feet dragging and undermining. It wasn't in a malicious way but its hard to go in and disrupt the "old school" way of doing it.
With all that being said, the more customers you get, the easier it gets. The early ones can work with you to build out case studies that let you narrow down the key benefits and that can be used to sell new customers.
My friends that successfully sell software for a living often sell software that everyone already owns a version of and they know exactly who to speak to. I think those are the two hardest parts and once you can get past that, again, its just about saving time, saving money or making more money.