ok, first off, try all local brewed beer, avoid IPA's until your ready to put hair on your chest
If you must drink bottled, try out sam adams, they are technically a "microbrew" but they are pretty mainstream and can be found everywhere. Try all other microbrews too, if you are at a store grab a six pack or maybe just a single bottle. Good beer comes in bottles, not cans. Maybe you arent ready for microbrews yet, you probably need a good year or so of "light" beer and Mexican piss water Coronas before you learn to appreciate the good stuff.
If you live near a brewery or have access to their brews.
Start with the signature beer usually the lightest colored ale, than go to the wheat ales, add an orange or lemon to your drink and work your way to browns. Finish off with a Porter, I like to call these, my dessert beer, cause they are my fucking crutch and I will drink them all day.
You might find something you like. I have found myself going to breweries and having a pint of everything on the menu. You can even request a sampler, they will give you a smaller glass with one of everything.
If you cant find a decent establishment, try guinness mixed with bass, its called a black and tan. I would recommend this to you first, but I would rather you experiment and than go straight for the good stuff.
Try all "seasonal brews" right now it is october. You should be able to find Halloween ale, Pumpkin flavored beer, Octoberfest, you also might be able to catch some leftover summer brews. You want to build up your tolerance for the winter seasonals because frankly, they will kick your ass and are around 6%. A real beer drinker avoids light beers unless they are playing beer games or is trying to stay sober. I like to smell my beers first, if they smell vinegary or are flat or soury return them to the bar and request something else, the tap line is fouled or the keg is kicked.