How do alcohol effect youwhen your driving?

One of the first effects of alcohol is reduction of the ability to make good choices (judgment). Shortly thereafter, the ability to censor behavior is reduced, which makes one more prone to rely on emotion instead of common sense. Along with those comes degradation of reflexes that are necessary to drive safely.

Altogether, alcohol removes most of the skills necessary for safe driving, and that happens early in the period of consumption. As more alcohol is consumed, things get worse.