Here is a way to create flame effects using Ron Deviney's Smoke photoshop brushes.

Create a new document with a black background. Create a new layer, select a nice bright red as your foreground color, and use one of Ron's smoke brushes that resembles a flame (I used the second brush in my example image), clicking once on the canvas.

Duplicate this layer twice. Lock the transparent pixels (click the first little square icon at the top of the layers) on these two layers. Fill the first duplicate layer with a strong orange, and the top duplicate with a deep, bright yellow. Change the layer blend modes:  the orange layer to "color dodge" and the yellow layer to "vivid light."

You should now have a decent looking flame that you can use in your images over a dark background (copy over the three flame layers). Or alternatively flatten the image, so you have a flame on a black background, and use a lighten layer blend mode such as "linear dodge" to blend in the flame with your image.