When I take pictures of people, the yellow and red tones seem to be enhanced and the result is a more jaundiced complexion in best case scenario and orange and a bit shiny if their skin is a bit oily. This only occurs with flash on. Is there anyway to remedy this situation, because sometimes I need flash on. Could it also be the orange autofocus light's fault?
Its unlikely to be the autofocus light, unless something is broken.
Its probably really white balance. If you shoot raw you can correct it in post-processing fairly easily, which can keep you from having to throw out shots that have good expressions.
You can try using a piece of white cardboard (say an index card) to redirect the flash up onto the ceiling, if its painted white. Do it as an experiment, just to isolate the cause. Of course, if the ceiling is purple, then expect a purple cast to the photos.
It can also be result of low quality flash. I'm not sure about the physics behind it, but what happens is that flash of light does not contain whole spectre of light and as a result you have some colours lightened more and some less. It can result in orange skin, but it can also lead to other colour anomalies.
I'm sorry for not giving more information, it's been some time since I used flash. I hope this can be helpful enough to lead your research
It's worth noting that most cameras ignore your white balance setting when using a flash. Exceptions are typically for "set" white balance relying on a test exposure of a white surface that is typically taken using the flash (when flash is set explicitly).
The camera typically expects a certain color temperature from an external flash and is likely producing what it expects when using the internal flash. If your external flash has a lower color temperature than the camera expects, you'll get reddish tinted results.