I disagree Ghost, and I do so for several reasons:
A) Pipeline is a fairly complex map requiring a buddy to play with and tag along and still you will get confused.
B) The way pipeline is set up if close quarters combat, for the new player this is a very difficult thing to learn, where to look for enemy and where not. Most people i see get frustrated from constantly being flanked.
C) New players need a straight foreward map that is easy to comprehend.
In turn I recommend the map "Bridge Crossing". It is a simple map, only one way to go so no confusion. Assault's job is to get to the end and Defense's job is to keep assault at bay. There is not much Close quarters (which is good because all most new people have experience with is the target range, which is medium-long range.) The only bad thing about it is that people "spam" M203 rounds at the beggining of the game at times but as long as you play smart and head the non-beaten path you will not get hit. Also in Bridge Crossing your using the M16 or M249 SAW, which are the only weapons you have really been introduced to (unless you went ahead and did ALL the training). That basically sums up why I disagree : P.