Depends on what sort of zombies. Judging from all realism, let's assume that we're talking super-rabies shambling zombies. These seem the most likely to happen.
First, depending on the time of the year, there are different environmental aspects we have to take into account. If it's cold, the zombies will likely freeze relatively quickly due to their lack of ingenuity, if it's hot, they will dehydrate quickly and their muscles will lock up.
Secondly, are they really 'dead'? If they are, we can count on rigormortis to affect their mobility as well as muscle deterioration. If they are not, we know that they must have a pulse and blood flow, therefore we can assume that you can bleed out a non-dead zombie. You may also be able to poison, drown, suffocate, or use disease to combat them.
Given those two facts, and that the zombies are normal people who have likely lost most of their mobility due to the zombification process, we can easily counter this invasion with a few simple methods.
1) The Zombie Antithesis is a Shotgun, or a nice Baseball Bat. Both are easy to use and provide massive physical trauma for the end result. You've likely swung a baseball bat in your life at least once, and so it should be a natural weapon. If you're up against a few scattered shamblers, it's time to play homerun derby. Except with their heads.
2) Against a big group? Run, Run, and last but not least, RUN. They are much slower than you and if you do not allow yourself to be cornered, then you will make it away just fine. Cardio is your friend, as is knowing the layout of the streets you are living on.
3) If you see someone bitten and it has been determined that zombieism is contagious, fuck the moral issues and put them out of their misery. Would you rather die human or be a mindless cannibal? I know what I would choose.
4) Don't form large groups. This one is a no-brainer. Too many people means too much conflicting interest, and too many safety oversights. It's much easier to manage a smaller group than a larger group.
5) Learn how to barricade and where the nearest hardware store is. If you can fortify an apartment complex, you can support yourself and your group.
6) Learn to like preserved food. It's what you'll be eating for a while.
Taking all of this into consideration, you really only have to wait the zombies out. Eventually they will be killed by the elements, starvation, and decomposition (if they are dead.) I estimate that given the average human has to drink water every day or die, if they are 'living' zombies, it will be maybe a few weeks before the infection dies out (mostly). At that point, bodies should be burned. If they are dead zombies, it may take longer, but they will eventually shrivel up and decompose to the point where they can no longer move. At that point, bodies should be burned.
In either case, it's a simple strategy. Suit up, barricade in, and turtle.