Basically, you should;
Know the system, especially character gen rules, inside and out.
Develop the PC with the player every step of the way, including skill selection. I have a skill sheet that I precreate listing all the skills I allow/use in the game, yet I have blank spots, so new skills can be added (such as for lores). I also let it be known new skills can be created (such as Lore-Magical Beast).
Over view and rubber stamp everything.
Offer firm direction. Even in RM2, a beginner is prone to over stretch a level one PC and end up with a total milktoast.
Make sure the PC is good at something, preferably what the player wants to be good at. This requires good communication between player and GM.
You do not need a sample combat (I hardly ever ran one because while I like a good rpg fight, the strength of the game isn't JUST combat and I never want to give the ole ADnD idea that might solves everything), but you do need to stress to players that RM attempts to simulate realistic combat. I often point my finger at a player and tell them to pretend this is a machine gun then ask who wants to charge me? How many think they would just suffer a few hit points and then get to hit back? What if it was a single shot shotgun? Who is willing to die so the others may kill the foe? They will get the point.
When the games start, coddle them a little, but DO NOT LET THEM KNOW IT. That first fight can be a cake walk and still show just how lethal combat really is. Remember, it isnt the damge you do to them, but rather every time you pick up the dice to roll against them...every player feels that tension at that moment, and in RM, with maining and instant death right around the corner, that feeling is intensified. It is the roll, or the knowledge of the roll can portend that really matters, often far more than the results.
lynn