tl;dr Have a nice looking product, clear target audience where you bring real value, be consistent, send reminders quite far apart.
We had many failures and sent many emails that no one answered.
With Welder (https://www.getwelder.com/) we finally succeeded and got B2Bs to try our product and validate with us.
First, we needed to find out who is the potential target market. So we created a video ad that we ran on the YT video of GaryVee where he talks about the importance of content. Most importantly he was doing it completely remotely. Thus people who watch it could have the intention of creating content remotely.
Thanks to that we saw a variety of signups and between them B2B signups as well.
When there was a clear pattern in which B2Bs are signing up we hired a guy to find more of them on LinkedIn, list them and reach to them.
The email was pretty short, straight to the point that we believe Welder will be a huge asset for them and that they should jump on a call with us.
The important part was sending 2 reminders that were quite far apart (7 days). And most of the responses we got were from these reminders. I believe the people were in a different place in their life (maybe more time, less stress etc).
We sent about 400 mails, got 60 responses, and 30 solid interests in the product.
I also believe that design is the easiest way to build trust. And that the good looking LP we have helped us a lot.
So, good product that makes sense for a clear target audience and then a lot of consistency.