These factors are highly dependent on your location, sometimes more so your city rather than your country. So, first of all, you should tell us which country you are from.
Secondly, as someone who have completed their AS-Level, you obviously can't teach in a school or academy. If you're not in for the money, you can take part in an internship for community service or an educational internship. Both would make your resume shine and glimmer, especially make you feel good.
That could involve you teaching the deprived strata of your society, as well as general welfare of your society.
If you want money, you will need to work harder than an internship. You can offer to teach O-Level/GCSE or younger students, possibly in your own school. You can talk to them on an one-on-one basis or print fliers and distribute them amongst your peers. Your prices should probably be based on how long you're willing to teach. If you'll teach everyday and can teach a couple of hours or more, the prices should probably be per week or per class. If you wouldn't teach more than an hour and on weekdays/weekends only, then your price should be per hour. Make sure your prices are considerably lower than the professional tutors and teachers in academies or cram schools.
You should also think of where you would teach--you'd probably want them to come to your house, in which case you and your family might need some kind of agreement to handle the children. If not, you should have conveyance to go to the students' residences.
