Try finding a method of revision that you enjoy. Writing notes for hours on end will get boring so try doing a creative method of revision. Mind maps and revision posters can be effective as they are fun to do and help you study. Also try incorporating colour into your revision as it will help you remember key details.
To prevent procrastinating, turn off all electronics and put them somewhere out of sight. If you can't resist using your electronics, ask a parent/carer or other family member to keep them whilst you study.
Also take 10 minute breaks every 40-50 minutes, to grab a snack or de-stress.