I did pretty much a straight burn to the moon the other day. The moon was almost directly over the space center so I decided to attempt a straight burn since I knew my ship could produce the Delta V and and had more fuel than needed for a standard Mun encounter. I set the Mun as a target and burned toward the prograde target marker on the Nav ball, it was about 5 degrees off center toward 90 at the time. About half way to the Mun I had to do a coarse correction for an intercept. Since I was aiming for an orbit I did another correction once my ship got caught by the Mun's gravity. So it is possible but I had to burn way more fuel than normal, almost double the amount, when accounting for the coarse corrections. With a bit more practice I probably could do it better, but I think I will stick with the standard Mun encounter burn from Kerbin Orbit. It gives more time to set up a maneuver with a better Mun Orbital trajectory.