Main thing you have to be careful with is to make sure your shutter speed is high enough for the longer shots to limit blurring due to camera shake. The rough rule of thumb here is it should be at least 1/n of a second where n is the focal length with IS turned off; note this would be the effective focal length so for a crop body you have to apply the crop factor of 1.6 for Canon. With IS on it gets you maximum 3 stops reduction in this but in my experience you should only ever really halve it. One thing to note about IS is that it takes a little time to settle down after activation so when you take a shot half press the shutter button then pause for a second before taking the shot to let the IS settle down.

Outdoors its always a good idea to use a hood because on bright days it lowers the chance of lens flare and also protects the end of the longer lens from hitting things; it does happen and a damaged hood is easier/cheaper to fix than damaged glass. For indoor work extra focal length gives you a lot of possibilities but with a slower lens like this you will have to pay particular attention to lighting. This is why pro photographers go for faster and way more expensive glass like f/2.8 because it makes lighting less of a concern.

Best thing to do is just start using it as it will take you a little time to get used to the weight and balance of the new lens on your camera.