As soon as the patient starts entering the vehicle, speed off towards the hospital - You don't have to wait until the patient is securely in the vehicle before driving.
Make sure that either the passenger door or the back door of the ambulance is right beside the patient, so as to reduce time loss - This is particularly effective when the patient is elderly, because they walk very slowly. Goto the injured patient and stop beside him/her.
Various statistics are shown on-screen, and an injured patient is represented on the radar by a blue blip. Once you are inside an Ambulance, toggle the paramedic missions. You can do these paramedic missions wherever you like, but Angel Pine is the most sensible choice as it is small, remote and easy to get around whereas (for example) San Fierro has steep slopes and lots of traffic. If you can't find one at Angel Pine get one at San Fierro and drive it to Angel Pine. In this guide you can learn where to find them, how to activate them and of course, the best way to defeat them. Some are required for 100% completion and some are not. There are dozens of odd jobs available in San Andreas. GTA Online Double Cash and RP Event Weekend GTANet Exclusive PC Screenshot from Rockstar MTA: San Andreas Deathmatch - Developer Preview