First off you need to know the rules.
1. If you live in an apartment, condo, or any other type on home that is connected to other homes you need to see what the rules concerning reptiles and snakes are. (You mother may be saying no do too these rules.)
2. If you live in a housing development you need to find out if and what the rules are for the home owners association.
3. If you live in a city or township you need to find out the rules about it for the city or township.
4. Now you made it to county laws same process.
5. Finally state laws come in. I seem to remember someone saying Jersey required a permit for having a ball python.

(All the above info will really impress your mom if you have it, it may also help explain why your mom is really saying no.)

6. Now find out about enclosures and setting them up. Collect all the info including price. A quality enclosure can go a long way in easing your moms mind when concerning escape.

7. Find out feeding options. Some parents may be appreciative of the frozen thawed type of feeding since you will not have to bring live rodents into the house, others may not like it as that means their freezer will hold frozen rats as well, but that can be solved by getting a dorm frig with the little freezer on top to house your Ball pythons food.

8. Make sure you can afford all of this on your own and do it all on your own. Parents normally say no to any pet due to cost or work they will have to put out. Even weekly trips to pick up food can get old quickly.

9. Collect all the facts you can find on ball pythons and why they are good pets and facts on why your parents don't have to worry about injury to you or any other member of the family including pets.

10. Now present your case to your parents. Make sure you stay calm and do not get overly emotional or defensive. If the answer in the end is still no, stay calm and ask what it would take in addition to the info presented to convince them that a ball python would be a good pet for you. Then do it if at all possible.

You never know through all the research you may find a ball python is not what you want. In the end if you still want to own a ball python you will have the knowledge to make you a better keeper.

Be ready though as your parents may just have a phobia of snakes and nothing you can do or say will change this. Being considerate of their position can go a long way in the long run.