I said NO to drugs...
After 7-8 hours of trying them, I quit. I give up on drugs. I might try them 10 minutes or so out of evey month, but otherwise, it's over!
Anyways, now that I'm not being a smartass, I think the S-License tests are very hard, but you shouldn't give up on them. If you need to, have a friend come over and help you with them. It took me, and 5 other people to get all of the S Licenses on my GT3, but it's worth the time it took...