My first suggestion would be to visit all the reputable LBS (Local Bike Shops) in your area and start your search there.
Most good shops will allow you to take something for a ride and some bike shops will rent bikes for the day or weekend, which gives you a better feel for the bike.
After you get a feel for what you want visit the forum that fits.....commuting/road cycling/mtb and start asking questions there.
Welcome to biking and good luck.