your pictures are fine, there are just some small adjustments you need to be making.
Picture one, a levels adjustment and maybe a small contrast/saturation bump would help that picture a ton.
Picture two, the white balance is the main problem here. Use tungsten white balance when shooting under normal light bulbs.
Picture three, looks like you were using evaluative metering? The picture is exposed to average the scene but the reflection from your coin is much brighter than the rest. Since it is small it doesn't get enough "weight" in the evaluation and gets overexposed. exposing it properly would underexpose the rest of the shot though, so pick your poison.
I really like your first one of the controller, looks like it could be a great stock photo.
As for getting used to the camera, read the manual often, and experiement with custom settings, or whatever you canon users call them
try out different things and learn what your camera does (ie. evaluate the scene making your small subject underexposed or over exposed, depending on the rest of the scene). Really experience is the best for this.