Another saddening point to consider is that most people in a resistance role will not have the training to successfully make long range shots. Your success rates will likely be much higher at closer ranges.
However, being largely true doesn't mean completely true. Why are we having the debate about the 5.56 being inadequate in Afghanistan? Why are the Taliban and Haqqani fighters choosing Enfield rifles over AKs? Personally I'll keep taking my chances with the illiterate goat humpers as opposed to the folks who show up to my left and right at the High Power matches.
Because closer is deadlier for both sides. By choosing antiquated bolt action rifles that outrange an M4 the bad guys are able to maintain "standoff." In Desert Storm the Iraqi Army was obliterated on the ground, even tank on tank battles were one sided because of "standoff." If you go to any website or reference book about the capabilities of US Tank Crews, you'll see a "maximum effective range" listed that is *ahem* highly conservative. Similarly other "maximum effective ranges" are for planning purposes only. The "maximum effective range" of the m24 sniper rifle has been listed as 800 meters for years even though I have yet to meet a sniper who doesn't have data on the m24 and m118lr out past 1000 meters. For what it's worth the old m118sb ammunition was less accurate, but still capable of 1k shots. I know snipers who have data out to 1400 meters in their data books.
To a very large extent the hardware you have available dictates tactics. If all you have is a pistol that limits your options. When you have an international network of financiers and weapons smugglers funneling Dshkas, RPGs, and SVDs into your organization that opens up possibilities. The Taliban may be illiterate goat humping cavemen, but they do know how to pack a Dshka up a mountain to conduct a long range ambush. A large portion of learning to use terrain is learning to minimize the standoff advantages, or to gain a standoff advantage (hence climbing a mountain with a Dshka).
There really is a manual labeled "Tactics" http://www.globalsecurity.org/military/library/policy/army/fm/3-90/index.html and it is a good place to start for thinking about how men, weapons, and terrain interact. I won't say that the terrain will dictate the tactics you use, but if you are going to do something "audacious" you had better know if the terrain will support that. The 6th Rangers crawled several hundred meters through open fields on their approach to Cabanatuan, and the German Army displaced an entire battalion undetected through a single hole in the wall to set up a base of fire in Stalingrad, all because they knew that they could get away with it because of the terrain.