Experience: Working 8 years out of an Air Force ER with primary ambulance response and air transportable hospital duties.
What always worked well for me was to use landmarks to find the pulse. Go about 1" proximal to the base of the palm (There may be a crease line there to use as a mark), and to the lateral side of the wrist. There is a tendon there, I went a little to the outside (lateral) of that, palpated with the fore and middle fingers.
Pull gently towards the tendon and slightly down, and you should feel the pulse. I also (as a personal preference) kept my fingers just slightly separated (Maybe 1/4" or so) as I felt that gave me a better feel for the pulse. As far as being able to distinguish it in a distracting environment, you just learn to shut that out.
All of the above assumes that the patient is not compromised to the point where you won't be able to feel a radial pulse no matter what. In that case you would need to go to brachial, femoral or carotid.