dude i remember that feeling soo much the first few sarges i did in rules of the game missions
i think what its down to was the fact that it was your first approaches, especialy day game can be hard to open as people are often in a rush or have somewer to go or someone to meet. so in order to open and reach the hook point you need to demnstrate alot of value so thel stop what ther doing and be interested in the convosation.
relax this was your first time opening and even tho you may have froze you still opened, try a few try'd and tested openers to get yourself comfotable, personal fav of mine is the jealous girlfriend opener, not only it is interesting as is almost like gossip but you can link it to other openers if the set doesnt hook. also a good tip for me was to work on the transition, as the transition from an opener is just as, if not equaly important.
but just relax, the feeling your getting is due to the fact that you know why you are there, just relax and eventualy you will calibirate more and find it easy
good job on getting yourself out there m8
