Lets be honest, a clean sound electric guitar can be a little dull, that is where a guitar effects pedal comes in. There are many types of guitar pedals on the market, but don't be overwhelmed, there a few basic categories that once known will help you to narrow down the sound you are looking for.
Firstly, you should consider an overdrive or distortion pedal. Practically the same thing. An overdrive pedal replicates the sound of an overdriven tube amplifier and has a more subtle distorted tone than classic distortion pedals. Pedals titled 'metal' take distortion into heavy territory.
Beyond the crunch you should consider some modulation or delay pedals. A delay pedal is quite straight-forward, it adds a delay of your signal to the sound. Analog delays are often best and can add real character to your sound. Modulation effects such as phaser, tremolo and flanger guitar pedals bring in a whole new palate of spacey and spiraling sounds.
A tuner pedal can be a handy stage accessory and everyone rock guitarist needs a wah-wah pedal. Don't forget to grab patch cables to link your effect pedals together. A 9v adapter with a daisy chain is also a must, enabling you to power all pedals in your chain from the one power supply.