Just Can Not get the Light Right

In the first image above light is coming in from a window camera right. In addition, a strobe in facing the model also camera right at an elevated position. Although the image is well exposed, it gives the somewhat different look that one might expect if the photographer wanted to have the main light appear primarily from the window. This can be tricky if one is working quickly, such those who attend workshops and may not have total control of the set.

One option is to use overlays with light rays. Photoshop and some other editing programs do have the ability to form light rays however this can be a time consuming process, especially if you are creating the light rays from scratch. One option is to choose a light ray package in an overlay set. Overlays are images that come in the form of a typical photo shot in a certain method, or are also available as files with transparent backgrounds (PNG). 

Files with solid backgrounds are typically 'embedded' into an image using one of the blend modes such as softlight (Photoshop). PNG files typically do not need a blend mode unless further refinement to the image is necessary. These light ray images can flipped, rotated, sized to need and placed anywhere within the base image. In this case, the file was rotated and sized to make the light appear to be primarily coming from the window. The darker area appears on the wall behind the model to simulate actual light fall off.

Overlays are available from many sources including Etsy, which often provides once of the lowest cost for download packages that often a high quality product.