Building confidence on the mats
When you're learning a new move it's always a good idea to work up the ranks. Meaning you can't try new and developing moves on purple belts or brown belts. They're not going to let you hit them and it will be shut down right away.
You have to start drilling them on white belts and when you're confident enough you can work up to blue belts and purple belts etc. This is the best way to do it because they will resist during sparring and they will react normally.
As you go up the rank it will gradually become harder and harder. They will resist and shut it down. But you will find ways to eventually counter their counters.
For example:
I started using De La Riva (DLR) a lot. But it was so difficult to even enter DLR I couldn't even practise whatever I wanted. So I had to try it on white belts that has no idea what they're doing first so I can enter it first and attempt a sweep or back take.
Once I drilled it for about a week or two and fix up some of the problems I had, my DLR guard got better. I didn't have to think about what to do, or how to enter it. I just know it's there and get into the position.
I'll be able to understand the various reactions people will have and find ways to counter them with either a sweep or transition to another position or even taking a back.
Once you're comfortable with hitting them on white belts. start it on blue belts. Because they will react differently and they will be even more difficult counter. And you try it on them for another few weeks and move up the ranks one at a time.
But be patient and go slow. It's going to take a lot of time to develop any new techniques.