The first thing you should do is throw away all your smoking gear such as papers, bongs, rollers and anything else that you may use to set up your cannabis. Don't throw your left over cannabis in the bin but make sure you flush it down the toilet as you can't retrieve it from there.
You must also make sure that you have your support system in place. Tell your loved ones and friends what you are doing and ask for their help and support. Make sure you also tell your “smoking” friends what you are doing and request that they respect your decision to quit, after all you're not making them quit.
The good thing is that withdrawal from cannabis doesn't last that long, the first three days are the worst and then it will level off after the first week and by the second week you should feel much better. Prepare yourself for any withdrawal symptoms, research the effects and know how to give up cannabis successfully. Remember if you are fully prepared you can give it up.