Dilettantism is the mark of the amateur. Avoid needless embarrassment. Practice the correct pronunciation of your god's name in the privacy of your room before chanting it in public.
Flash cards are often helpful.
Never invoke anything bigger than your head. Avoid all cabalistic jewelry over ten pounds in weight, you're just asking for trouble. I cannot stress this enough. Pastel-coloured candles in the shape of cute animals are like beacons to the Dark Lords. Ransacking hotel rooms is probably safe, but going 'round to beat up the good guys is a sure route to the bottom of the Thames.