A photographer is mean to make the subject look good. This might not always mean attractive in the conventional sense, but it helps. It is possible to make the overall image look good without every subject in the image appearing to be an attractive individual, but if we can make the individuals look attractive, all the better.
Tricks, as with any art-form, need to be invisible. We should get the impression that the person looks like the image, or at least they looked like that on the day. If you do use Photoshop, use it sparingly. By all means cover up the occasional acne blemish, but not a birthmark.
Wrinkles are an issue with every person as they get older. If you photograph a wedding you will have grandparents and other relatives to appease. These people weren’t always old, and probably don’t like to think of themselves that way. Rather than Photoshop out the issue(s) try to use natural light while taking the shot. If light is directly on the face the wrinkles are less visible. Light from other angles can emphasis the shadows, and make for unflattering facial images. If you want you can augment the natural light with a flash or reflector.
Normally out brains adjusts what we see according to the context. When an image is framed as a photo a lot of context is left out of the frame and our brains does not compensate in the same way. Looking at what is isolated in the frame is a large part of getting a good image.