It's always tempting to collect the various characters you find in a game like this one, and sometimes there is a real reason to do so because they play differently. Here, though, the characters all function the same. The only difference is their appearance. They are still fun to gather, of course, but there aren't any extra incentives.
Clock Exploit
As in many mobile games, the content you unlock is determined by the amount of time the game believes you have played. You can head to your system settings and move the clock forward a couple of hours to earn additional free coins, which makes it easier to unlock new characters. Do this often enough and you'll get everything, without going through the trouble of actually playing the game.
Only Watch Some Ads
You can watch ads to continue a run if you happen to die, but you're better off taking your lumps and trying again. Instead, save the videos for those instances when they can earn you rewards, such as a pile of coins or even an extra character. That way, you don't have to worry about running out of ads to watch just before one might have awarded you with a nice bonus.
Portals Are Optional
You will come across portals that you can enter on your quest, and sometimes it's a good idea to do so. Other times, however, you should steer clear of them and proceed in some other way. Only enter a portal when you need to in order to find your way around an obstacle, or else you could warp to a worse situation than the one you were hoping to avoid.