Pessimism is coming from the media! Good news is not newsworthy. Some of what you are describing is regional. Do you think things are that good in a city where there are plant closings or an industry with high unemployment?. Not all professions are doing well! I think you are describing successful people rather than the economy. Success generally has very little to do with how everyone is doing. I go to some of those crowded restaurants too. I wonder if the sales are the same or just busy. Everyone could be spending less than before.
Keep your costs down. In order to turn a profit on what you're selling, choose to sell an item that's inexpensive to make. Lemonade is a classic because all of its ingredients (water, sugar, lemons or lemon juice concentrate, and ice) are fairly cheap and easy to obtain. Popsicles are another favorite because they can be bought in large quantities from the store!
Don't sacrifice morals for a quick buck — At the outset, you'll want to do all sorts of things to make money online, but don't sacrifice your morals for a quick buck. Not only will you put people off, but you'll lose Google's trust. You also shouldn't concern yourself with things like Adsense or other ads on a blog before you have around 100,000 visitors per day. Yes, per day.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.