A visit is still the most obvious starting point - either to the bricks and mortar store, or to the company's website. You can learn a lot about your competitor's products and services, pricing, and even promotion strategies by visiting their business site, and may even be able to deduce quite a bit about the benefits your competitor offers. Go there, once or several times, and look around. Watch how customers are treated. Check out the prices.
You can also learn a fair bit about your competitors from talking to their customers and/or clients - if you know who they are. With a bricks and mortar local competitor, you might be able to find out about the reasons customers buy from them by canvassing friends and acquaintances locally.
Other good "live" sources of information about competitors include a company's vendors or suppliers, and a company's employees. They may or may not be willing to talk to you, but it's worth seeking them out and asking.
And watch for trade shows that your competitors may be attending. Businesses are there to disseminate information about and sell their products or services; attending and visiting their booths may be a excellent way to find out about your competitors.
You'll also want to search for the publicly available information about your competitors. Newspapers, magazines, and online publications may all have information about the company you're investigating for your competitive analysis. Press releases may be particularly useful. 6 Ways to Find Out What Your Competition Is Up To provides even more tips for gathering the information you need.
Once you've compiled the information about your competitors, you're ready to analyze it. Tips and instructions for analyzing the competition are on the following page.