Starting Clomid

Sophie • I`m a teacher. My husband is a pharmacist. We have not used bc in 3 years...
Ok, so my husband and I have been TTC for a year now. We have both been tested and both of us are In the normal ranges. We, apparently, are the 20% of couples that are having difficulty without a medical reason. I'm ovulating normally and DH is very potent.
Anyways, my next cycle starts this weekend and I'm going to start Clomid for the first time. I'm a little anxious about it.
For those of you who have used it:
What were your side effects, if any?
Any suggestions or words of wisdom?
How long did it take for it to work, if you were successful?
What have you heard about having twins while on Clomid?
Any information about it at all would really help settle my nerves. 
Thanks