Keep a record of the activities that you were doing when the attack occured. This enables you to look for a pattern. Avoid factors which may make it worse for example, cigarette smoke, petrol and paint fumes, cold air, perfume, aftershave and pollution. Try to avoid exercising in the cold, if this is not possible consider using a face mask or a ski cap. It is quite common for an asthma sufferer to have an attack after having a cold so take active measures to avoid getting a cold.
Stress is another common cause so take up yoga and actively make efforts to relax.
A moderate amount of caffeine is therapeutic althought don't overdo it as this may make your asthma worse. If you are prescribed asthma medication by your doctor - use it, it helps to relax the muscle tissues and hence making breathing easier. Exercise is vital provided your doctor has said that you are able to undertake regular exercise. Try sports such as walking, swimming and golf. There are certain breathing techniques which you may find useful if you feel your breathing becomin laboured.