Because the score is calculated as 10 times the square
of the number of disappeared bubbles, attach as more
as same colour bubbles and then clear them away.
When a new game begins, check the numbers of four
colour bubbles, leave the most kind bubble at the
end in order to attach as more as same bubbles.
Don't
use bombs at the beginning. Leave them to the end
of the game, because they will help you to clear away
the single bubbles. It seems much easy to clear away
all the bubbles and win the game.
When you clear away all the bubbles, you Win, and
you can continue the next game.