I've been prepping H2-blockers before drinking since '95, and have gone through numerous trials and errors to find the right "regimen" for best alcohol tolerance. Although this method may not work for everyone, it has worked quite well for me.
First, take the H2-blocker [I use zantac (generic- ranitidine) 75 - 150 mg] ON AN EMPTY STOMACH approximately 20-30 minutes before drinking.
Second, eat some food approximately 10 minutes after you've taken the H2-blocker. This gives time for the medication to be absorbed and also decreases the rate of initial alcohol absorption. I noticed that if you start off drinking light (like beer) first, then you can hit the hard stuff as much as you want later.
Third, proceed to get intoxicated.
If you plan on a long night of drinking, bring an extra pill of H2-blocker, you can pop it approximately 3 hours later
Oh yeah, please drink responsibly, but if you can't, for god's sake find a designated driver. Happy drinking.