Using the back room is key, if only because it has a door.
You can either wait until they knock it open, then shoot someone in the head, kick them all back, then retreat and repeat (keeping an eye open for anyone dropping in from the ceiling, but there aren't many, and you should be able to deal with them so long as you notice them).
Or you can let one get through the door before you knock the rest back, leaving you free to take him out (either headshot-kick-knife on the floor, or legshot-knife/suplex).
Once the enemies die down, head out and see if you can lure any more back after you. Finally, take out the archers from under one of the balconies, so you can shoot down any arrows they fire at you, and not have to worry about the other one.
Another tip to remember is that the game remembers who you've killed in a room, so if you head back to the previous area, next time you enter you'll set a new checkpoint to reappear when you die, and the guys you killed will stay dead. It's cheap, but it also means you can backtrack and save before dealing with the next point.
As for the next section you should be saving your rifle ammo for, you can get by with the pistol, especially on Wii. The enemies are pretty weak, and if you aim at the legs, you'll keep knocking them down so they can't bother you. This also leaves you able to notice anyone charging for you.
---
On another note, anyone got any tips for The Mercenaries? I five-starred the village with Leon no problem, and I want to get all his levels out of the way before I move on to the fun characters. Waterworld keeps kicking my ass though, a combination of Super-Neo-Ultra-Chainsaw Man, archers who stun me so I can't shotgun him before he decaps me, and the guy with the rocket launcher.