Vintage patterns are many and varied, just like modern patterns. And we all get comfortable with certain design details and styles. Perhaps we like the style, or we just find it easier to sew garments when we're already familiar with those particular details. But it can be difficult to find vintage patterns that use the design details you're familiar with.
This is where Vintage Pattern Wiki comes in. This is a standard wiki site, which means it can be edited by anyone, but this one focuses on vintage sewing patterns. With the ability to search patterns by era, style, manufacturer, or designer, this is probably the fastest way to find what you're looking for.
What I love is the search function. You can type in certain design elements (try typing princess seams in the search bar), and you'll come up with a variety of patterns that contain that particular element. And there are usually links to online stores where the patterns are available for purchase. You can even sign up for a wish list for patterns that are currently unavailable. This way, you'll get a nice little e-mail telling you when the pattern is available.
All in all, Vintage Pattern Wiki is an excellent site that allows you to find vintage patterns. But don't bother searching for modern sewing patterns. Nothing newer than the 1970s is listed. It's Vintage Pattern Wiki, after all.