Know when to run
Remember: there's no shame in running, especially when it's part of your job description. There are going to be plenty of situations where you'll find yourself outnumbered, but one of the beautiful truths to Mirror's Edge is that there's almost always somewhere to run to, and a number of ways to get there. When an army of Blues are standing between you and the next checkpoint, make sure you have a carefully planned strategy in mind before launching head-first into their fire. Wall-running, sliding and vaulting are all invaluable skills when it comes to dodging bullets -- just be sure to avoid finding yourself clinging to a ledge or shimmying along a pole in the middle of a fire-fight or you're simply free-running target practice. Take advantage of how relentless the Blues are; they'll hunt you like bloodhounds, but are nowhere as nimble or quick as Faith, weighed down by bulky guns and armor. If a group of cops stand between you and your goal and there's no possibility of sneaking past them, lead them away with Faith's skill set: vault over fences, slide beneath ventilation shafts -- taunt them with your abilities until they're spread so thinly that you have a clear shot at your next objective.
Listen to your sources
Through most of Mirror's Edge, you're going to be doing so much uninterrupted free-running that it's tough to stop for a spell and wonder what's next on the agenda. That's where your boss, Merc comes in. Merc relays tips and locations to you via an audio stream and is guaranteed to keep you updated with invaluable information on specific landmarks as well as objects and elevators that can be activated in your local vicinity. When completely lost, press the X or Square button (depending on your console) for Faith to automatically hone in on your next objective, but remember -- this doesn't mean that a straight line is always the easiest way to get from point A to B. This is where your Objectives menu comes in handy, displaying a rough architecture of your surroundings, giving you a better idea of where you can and can't run.
Trust your surroundings
Mirror's Edge is a compilation of astonishing Oh my God, did I really just do that? moments where nearly anything is possible. Whenever you find yourself at a dead end or are faced with a large gap between yourself and your next target, take a leap of faith (no pun intended) as there's almost always a pipe, ladder, or cushion to break your fall and lead you to your next objective. Mirror's Edge is also a game largely based upon trial and error, so don't get down in the dumps if you fall sixty stories onto the pavement below -- it's all part of the learning process. Even when there isn't a streak of red in sight, keep in mind that the environment in Mirror's Edge is just as much a character as anything else the game has to offer. With this in mind, try mixing your free-running skills on the fly, such as wall-running followed by jumping to distant surfaces, vaulting over fences or crates and grabbing onto nearby ledges, or even swinging from a dowel into a wall-run before sliding down a bright red pipe. (Trust me -- it's easier than it sounds.) The environment can also come in rather handy when it comes to taking on enemies, as nothing says " Owned!" like kicking a Blue in the face and watching him plummet to the streets off of some less than sturdy scaffolding.
Above all, remember these words: as long as you keep your feet moving and your mind sharp, the futuristic world of Mirror's Edge should be, well, it won't be a cakewalk (or run, for that matter), but hopefully these tips will help you survive the Blues' reign, and bring order to the game's dystopian future.