Well, there are lot of problems on ambushing enemy patrols.
- Terrain.
- Forests are good for hiding and/or establishing of guerrilla base, but there is limited possibilities to engage patrols - you can not engage them from a far distance with a sniper fire, to see enemy you should be very near the edge of forest. Which means you have quite poor chance to retreat after attack, if you are acting alone. Moreover, enemy can mine roadsides with `Dragontooth` type anti-infantry mines... you won't see them in a grass, and they plastic container will be impossible to locate with metal detector...
- Rocky and/or desert terrain is good for long-range sniper attacks, but there is no concealment to make a base, there is no concealment to hide from the enemy aircraft.
- Surviving. It is not enough just to leave your home, enter the forest/mountains and ambush enemies. You need water, food, place for rest, without any of it - you are dead of captured. Or, if you are very lucky - only incapable to fight...
- Knowing of terrain - you need to know terrain where you are planning to operate. Without it you do not have serious advantages over enemy - there is a danger to retreat in a deadlock...
For example me as inhabitant of suburban area of ~1 million city... I have problems with ALL of these factors, even if I had an assault rifle and strong will to fight. I have a square 2x2 miles of forest on over side of street, but there is no water in that forest and forest is almost just like park... I have a pretty good knowledge of my suburb, but that could not help me much if I have to stand against invaders.