most of this has already been said above ... but to summarize
1 don't drink alcohol because it spoils it
2 you may be sick the first time you do E
3 maybe do a half the first time?
4 lots of water but not too much (but the only girl I read about who died from drinking water drank ~10 litres in 2 hours)
5 comedown can be rough ... like a bad bad hangover + depression ... be aware
6 have some chewing gum ready
7 do it with people you know, and who know about E
8 chill out have fun!
if you want to experience the rush without committing to the full trip, you can crush up a pill and snort a line of it - this stings like fuck and isn't generally recommended but it's ok once in a while
it will lower your inhibitions, you will probably start hugging all your mates and telling them what fantastic people they are and that you love them ... it's much more a love-oriented than a sex-oriented thing
good luck