One of the things I find most difficult is while we (designers and devs) are working in an iterative agile environment, getting a hold on users and customers and trying to meet them in regular basis is nearly impossible. Our product is a web app, SaaS type, exclusive platform. It not a public website and it has some technical lingo. The business is protective, there are people who think it could be disruptive to customer own work or it may diminish our reputation even though they may like to be a part of it. What is the best way to get in touch with customers where our company web site is not the gate way? By that I mean it is not really efficient to pop up a modal window and ask them if they want to help us with research because it is not visited by existing customers. How do you do it? How do you get a hold on a customer's contact data? How do you persuade the business that you have to do it soon and iteratively?
I had exactly the same problem during my last job. I was UX designer in a private company with SaaS products.
The lean UX methods helped me a lot. I followed it with the team and organized a workshop to build personas in a lean UX way : You don't have public datas, your customers are not everybody, they are a specific king of people and you, as designer, you can't find them just like that and share your screens on the net BUT you have another way to get users informations --> your team.
The people working on your company have a huge knowledge of final users, sometimes without knowing it. You can do a workshop with a member of each part of your company with colleagues who know with a specific point of view the users (sales know what users want and ask, consultant know how they use the product, support know the problem they meet, product manager can have datas and know their users...). All together you can create really reliable personas build on your global knowledge. (more details here) (lean ux method here)
Also you can contact your users by mail asking them if they would like to participate to users test. Depend on the number of people interested you can do users testing sessions and/or built an online demo to do it that you share in private and open a slack dedicated to your users feedback.
And you can use a track tool on your product pages to create the data you need.
Good luck ;)
If you have a sales team that interacts with your customers, talk to them. In a prior job our sales team provided a long list of customers for use to contact as test subjects. (In our case this was a list of people who had rated our company highly in previous surveys.)
I then contacted them via email to ask for volunteers. The first time we did this we got ~1% response. Then we told people that participants would be given a gift card and we got ~3% response.