You begin with 5 bombs, which should be enough. Be sure to use your bombs (RT) when necessary. Also aim to collect 1,000,000 points for the two point-related achievements. On your first play through, you should aim to stay alive for the full five minutes. Whilst all of the associated achievements can be collected in one run of Score Attack (5 min.), it is much easier to play through at least twice, focussing on different achievements. The speed will increase as you collect points, so you may wish to begin on Beginner and see how it goes. You can change the difficulty to either Normal or Expert, but all associated achievements can be completed by starting on Beginner.
Ignore Time Trial (Short 8) and instead select 'Score Attack (5 min.)'. More Time Trial Game Modes are still available, but you will no longer need to play them for any achievements. You should also have unlocked the 'Time Trial Cleared' achievement.
