Also don't mix your drinks that early! If your a lightweight you should stick to one drink all night... people who mix them are the heavy weights and the only way they can get drunk.
Pick a drink you like and yes drink it all the time, first few times itll take a few, then a few more, then a few more. Eventually you can drink it all night and wont do much to you...
Just rememeber though its crap having to pay like £30 to get drunk in a night, most wish they cud do it on a tenner...