You have a checkpoint on every 6th level of an area. So if you lose all your lives here, you will be able to restart from the checkpoint, rather than from the first level of that area.
When you see a ball flicker, this means it will turn into a bonus ball. Watch out for flickering through the corner of your eyes so you can quickly switch focus.
The bonus shots are not limited by time, but by number of shots (different per bonus). So while you won't want to wait too long, it can sometimes pay off to think well about where to use your bonus.
Try to get every fruit within reach, but don't make foolish moves that fill up your board. Fruit will quickly help fill the Zuma-meter to finish a level.
Chain bonusses (every consecutive shot makes a set of 3 or more balls; hitting fruit will not break the chain) can be quite a bit more helpful than you'd think. Sometimes it's better to take half a second to think, but rake up the chain bonus, which will fill the meter faster.
If you can make a triple or higher combo, the line of balls will reverse, giving you a short but welcome breather.
When the levels have become so hard for you that it is just trying to survive, just focus on raking up that chain bonus, clearing balls near the frond end of the row, and fill the meter as soon as possible.
If you create a gap between two balls of the same color, the whole line of balls will go in reverse.
When possible, shoot through a gap for bonus points.
Try to avoid shooting the last ball, until at the very end; shooting away the last ball will bumps the line of balls forward a little. In general, try to focus as much as possible on the front.
If you have balls that you can't use at that moment, it is generally better to just shoot them into nowhere, than to place them in the row.
BOSS BATTLE STRATEGIES
Boss 1: Kahtiki Kahn - Ancient Devil Idol
This boss is relatively easy. All you need to do is open a gap in the row of balls, and shoot the boss through that.
Don't worry too much about clearing the whole row of balls, since you won't be able too; just make sure it doesn't roll onto a second line.
Here, it is worth waiting for a combo, as it will quickly pull the whole line back, which is very convenient on a short track like this.
Wait for the boss to be behind a set of balls that you can create a gap in, and shoot him through that gap until he is defeated.
If you get hit by the objects he throws at you, you will be shortly stunned.
Boss 2: Maga Maga - Witch Doctor
The basic tactics remain the same with this boss as with the first, although it will be a bit more difficult since the first row of balls is now near you, in front of the second row.
It is even more efficient to aim for combo's during this battle.
On every odd hit (so the first time you hit him, the third, fifth, seventh etc.), the boss will summon two tiki's. Before you can attack the boss again, you will first need to hit both tiki's to disable the boss' force field.
If you get hit by his magic, you will be temporarily poisoned, and you will move the other way (if you move your mouse left, the frog will go right).
Patience, and trying to create gaps, is the key to beating this boss.
Boss 3: Baron Digo - Cannibal Idol
This boss is not too hard if you know how to play.
While you could try and aim for the boss with balls, this will only take half a heart piece per hit.
If you hit a skeleton warriors holding a electric ball, you will get an electric beam you can shoot straight at the boss, taking one heart per hit.
If you get hit by one of the boss' missiles, you will be dazzled for a short time, and the balls will constantly change color.
If you just focus on getting the electric beams, this boss will be done before you know it.