Look for the bubbles holding up a group
Matching three bubbles is useful. But before you shoot, look at what's hanging below them. If removing that group cuts every connection between the lower bubbles and the ceiling, they'll fall regardless of their colour.
A popped bubble earns 10 points; a dropped one earns 20. A small group holding up a large cluster can be worth more than a bigger match off to the side. Check for other supports too. Just one connection to the top can keep the whole group in place.
Use a wall bounce to reach past lower bubbles
The direct route to your target colour may be blocked. Try an angle that bounces off a side wall. It might give you a shot at a support higher up or an open pocket.
Look at the target group and the gap your bubble needs to pass through. If it clips a nearer group, adjust the angle a little. Keep the gap open so your next shot can reach the upper bubbles too.
Check the next bubble
The next colour is shown beside the bubble you're about to fire. Think two moves ahead: which group can you work on now, and which gap should you leave open for the next colour? If there's no match available, place your bubble beside another of the same colour to build a useful pair.
Don't block the only route to an upper group for a quick match. An open path may be more useful on your very next shot.
Misses add up between new rows
A shot that fails to remove a group uses up one of your allowed misses. A successful shot leaves the counter unchanged. Your miss allowance resets when new rows are added or you clear the whole board.
Watch the counter below the board. If you have one miss left and the bubbles are already low, a safe match is a better choice than a shot into a difficult pocket. There's no timer, so you can stop and compare your options.
Eliminating a colour means more new rows
When no bubbles of a particular colour remain, it stops appearing in new rows until you clear the entire board. Matches are easier to find, but the next batch adds two rows. Eliminate another colour and it adds three. That's the limit, even if you remove more colours.
After eliminating a colour, try to drop the remaining bubbles or clear the board completely. Work on the supports higher up instead of leaving isolated bubbles near the bottom. Several new rows can quickly use up the space you've made.
A clear board gives you a fresh start
An empty board earns another 500 points. The game continues with the starting rows for your difficulty, a fresh miss allowance and all colours you've unlocked. The next batch adds just one row again.
Your high score depends on good drops and how many of these cycles you can complete. Start on Beginner to get used to supports and wall bounces, then try a mode that allows fewer misses.