A lot of ammunition is required to defeat certain Bosses, such as the Joker. Conserve your ammunition for Boss battles. Instead of firing at enemies, run over them. Larger enemies will require one shot followed by a run down. Dealing with your enemies efficiently will make Boss fights easier. When you have to shoot an enemy, usually only hit is required to kill them. There is no need to rapid fire and waste ammunition.
Cards
You can use one card per run, which may help extending your distance and score. The Revive card is very useful, as it gives you another chance of running without losing your progress (score), together with Health Boosts that can increase your survival. Do not always use your best character. Alternate between cards and level each one up evenly to get a better chance of evolving from the start. Once a card is at level 5, retire it and work on the next card. Fusing two maxed cards will allow your character to evolve. You can use Evolution to evolve a card with another card in the same level. The basic card pack only costs 1,000 coins. It contains a variety of boosters and either a Batman or The Flash card. You will need those cards to level up and fuse cards together. When you have enough coins, you may want to consider purchasing the pack.
Coins
Tap on the missions to view their objectives. Completing each of them will result in a coin reward. Play the easier missions to begin saving coins. Do not spend coins on gadgets. Instead, purchase character cards to help evolve your characters.
Defeating Joker
Stay as far away from him as possible while he is throwing gifts. His range seems to be about two lanes from his vehicle. If a gift lands in the lane you are running in, jump over it instead of changing lanes. Shoot the Joker after he launches a rocket, during his two second reload time.
Evolution
When a character reaches level 5, you will be able to evolve their card if you have another card of the same level. You can also level up your characters with boost cards, however this is rarely required as you will gain experience by progressing through the game. Instead, save boost cards for the more complicated characters.
Experience points
Equip your best weapon with full ammunition. Running into a basic enemy will not cause damage. If you can spare the ammunition, shoot enemies to gain experience points. Leveling up unlocks more skills. Grind previous levels for experience points by killing enemies instead of getting a better score.
Gadgets
You can bring in extra gadgets after they are acquired. You can have one gadget card per use, and it will be used until you run out of cards unless you unselected. The most useful of these is the Revive card, followed by Health Boosts.
Gems
Connect the game to Facebook to get a 50 gem reward. You can also earn gems is by leveling your characters.
Movement
Instead of looking at your character, focus on oncoming obstacles and enemies. With the proper timing you will be able to dodge obstacles while still remaining focused on what is coming at you next.
Ammunition...