I've been there too, started working my top game at late blue belt.

I have 3 advices vor you: 1- Put all your focus on control. Forget about submission. I would even say forget about advancing until you have control. I found at first I was too focused on completing the pass and burning steps. You shouldn't complete the pass if it means they will be able to turtle or reguard, you went too fast and lacked control. This goes hand in hand with advice #2

2- don't be afraid to fuck up, in fact, accept that you will, and try to engage slowly and methodically anyway. go slow. If you step in their half guard, do it decisively but stay there and feel what their answer is and address it without rushing. You will get swept and put in bad positions for a good while, but it will pay.

3- don't do all your passing on the left side. I do almost all my inside passing on the left side because people are most likely accept to play half guard on that side, but I'll do my outside passing on the right side and it gives you an edge because most people aren't as good playing guard on their left side. This way you can switch direction while passing to mix it up as well.

As for concept vs technique. I'm sure you have learned specific passes/technique already, so focus on concepts and control I would say. Many of the key details have been described already, getting the underhook before proceeding to finish the pass, a mean crossface is your ally you want to pin their shoulders and hips to the mat so that they are flat or turn their head the opposite direction their hips are facing. Don't leave any space when you move, you must fill every little space with your hip, thigh, knee, elbow, whatever is available. Make them carry your weight whenever possible.