Timing Timing TIMING! This is the most important thing to any and every successful hair stylist in the industry. You need to be aware of your timing and to keep trying to get faster (without sacrificing quality). To become more successful you should actively keep track of how long it takes you to do each type of service and to always try to pay attention to how you're doing as compared to the last time you performed said service.
Take today for example, I managed to place a full head of foils and have it all process in just under and hour, but much to my shagrin there was minor bleeding righhhht along her hairline. Not such a big deal eh? Wrong, her hair would NOT take color and I had to try to repigment two separate times. Now I was doing very good on timing, but a small slip up lead to me doubling the time of the service.
Just try and keep sure you're paying attention to what you're doing and to not sacrifice you quality for quantity.