Just work hard consistently throughout the year in a nut shell. Really try to motivate yourself, don't imitate others that don't revise, because they'll be achieving poor grades whilst you will be achieving great grades because of your independent study. Reduce social life, and find out the best way you learn, as that is important. Go throughout the text book and additional books such as revision guides multiple times and towards the start of your exam do tonnes of past papers. I did all this and achieved an A in biology, so just remember, hard work beats talent when talent doesn't work hard. Five people in my year were kicked out of sixth form because they failed due to not putting in sufficient work