I would say that we should change the punishment for drug related crimes. I wouldn't say change the laws and make drugs legal or anything drastic like that. For one, if the government starts seeing tax money from them, just imagine how addictive they'd become. But changing the punishment would be the most effective use of resources. Right now, we're wasting billions on drug related crime. The price of incarceration alone and the strain on our prison system for drug crimes is ridiculous. Then add the cost of operating such an expensive and ineffective program like the DEA.
My solution:
Drug possession for personal use: couple hundred dollar fine, community service, suspension of driver's license until completion of drug rehabilitation (at offender's expense, of course), require notification to current employer, repeat as necessary.
Drug possession for distribution (dealers): couple thousand dollars fine, 6 month max jail time, probation, longer community service, suspension of driver's license/rehab (as above), report to employer, each subsequent arrest for dealing adds a higher fine and attaches all previous fines to be paid again. Make it unprofitable.
International drug traffickers: capital punishment
Most importantly, education!