The Rebellion PR Department

As I've mentioned before, there has to be a compelling reason for people to be OK with a high risk activity such as overthrowing their government. Your Evil Overlord (or colonising empire, or whatever) essentially must have crossed the 'Godzilla Threshold' in the public consciousness, to the point where the average person decides that an indefinite period of government instability and heavily armed people lighting things on fire and a major rebuilding effort is preferable to carrying on as usual.
Now, if this is more of a coup than a full-on rebellion-- ie, one powerful person wants to topple and replace the person above him-- one can see a scenario where the public is unwillingly dragged into a conflict that will go on whether they want it or not. However, if you've gone with the ever-popular intrepid band of upstanding citizens fighting the Evil Overlord (or have been issued this by history), you should really think about how they go about keeping the good will of the general population.
Before you say that they can get on just fine doing the hunter-gatherer thing, remember that an organised group which wants a regime change needs the following:

Supplies, such as food, weapons, warm clothing, access to water, and transport;Secrecy, even if it's only in the form of people who shrug and play dumb when asked if they've seen any rebels lurking about;Safe passage, again, even if it's someone just allowing the rebels to cross your property;Support after the regime change, when everyone is putting the pieces back together. Again, under some circumstances, the general public might accept a quick change of government, particularly  if the switch has little effect on their everyday lives (see my earlier frothing about evil governments who don't do anything actually evil). However, if this is a radical change that requires widespread action, there needs to be some level of public support, and the rebels should be working overtime to maintain it, or be shredded by public opinion when everyone is sick of the conflict.