I thought I would offer a little help to those looking for a bike. First of all I am a advocate of buying used. This is especially helpful when you don't know the options as when you're new to cycling. Buying used reduces your investment and allows you to try several types of bikes if the first one doesn't match your needs. If you have a lot of money and just want to buy something new, buy a used bike for someone who can't afford a bike.
The inspiration for this post is was a french bike I noticed for sale on Craigslist. When I see a motobecane or peugeot for sale I immediately get a red flag in my head. Here's the deal on that - threading. There are different standards for threading: French, English and Swiss. They are not compatible. If you're buying a bike prior to 1990 you have to be aware that it may be more difficult to get certain parts like bottom bracket and headset parts.
The typical bike has changed over the years. In the 60's and prior the typical bike was a single speed or 3 speed with wider tires and fenders. The English racer 3 speed was a classic and had narrower tires and lighter weight frame. The American balloon tired bike was single speed and had a focus on style and less on function. During the 70's 10-speed bikes took center stage and everyone was riding race bikes. The race bikes of the 70's had very narrow tires, dropped handlebars, Many of the American made 10-speeds had 27" tires. That's another red flag in buying a used bike. 27" tires are not on bikes nowadays. You can still get the tires and probably the rims, but you don't get the price and variety you do with 700c which have been used in Europe for many decades.
The third piece of advice I would give would be to try to buy a bike that is set up the way you want it to be. If you want fenders, racks, bags, special pedals it's best to find a bike that already has all of that included. I live in the Washington, DC area where there is a signficant cycling community. There's a huge advocacy group called WABA. There's a touring group with thousands of members call Potomac Pedalers. What I can find here is much different than what you might find in Wheeling, WV. The idea I'm trying to avoid is buying a bike and replacing a lot of parts. The price adds up quickly and the results are not satisfying for the novice.You might buy what you think you like and then you change your mind after you've spent the money and done the work to modify it. It's often cheaper and less complicated in the long run to sell your bike and buy another that's set up the way you want.