Basically, the best way is to cut all funding for buses and ambulances. This feature is grossly overrated and certainly not worth the cost. You might say to yourself, "But don't more schools cost more?". The great Sava says... "NO". They actually do not because you can control the local funding directly so that you effectively only pay for the education that you need to give your people.
It might be annoying to pay attention to more schools and to clutter so many in a smaller area, but in the end, it's worth it. I've done extensive experimentation with this, and I've found that 1 school with full bus funding effectively equals about 3 schools with 0 bus funding.
If your city gets to be a reasonable size, perhaps 20k, you might have about 10 elementry schools. Counting only the bus funding, you are paying 2,000 dollars a month in just bussing your students. With 30 schools, you pay 0 a month in bus costs. And even though there are more schools, you do not pay more per month in educating your sims because you control the local funding. Regardless of the number of schools, residential areas only put out a certain number of students.
The other upside to doing this is that you can cluster your residential areas in tight spots and control the flow of traffic and the distribution of zones much more effectively in your city. And also, if your schools or health care facilities strike, only a small area is affected while you increase the funding to meet demand.
Doing this is also better for when you start building up your city after you've filled it with low-density zones. If you have bus funding set to full, and you rezone your low density residential to high density, your schools will get maxed out easily and you will have to demolish existing structures and overlap them. So not only are you wasting money on bussing, your schools are overlapped and closer together anyways!
The bigger your city gets, the more money you save because of this trick. And the best part is, you can start doing this at the beginning of your city building... you don't have to wait for a budget surplus before adding these amenities to your sims lives.