So just what are the blending modes? 2 Words: Really Cool. Blending Modes are one of my favorite Photoshop tools and I use them all of the time in graphic design. I would say that I use them much more than the average Photoshop user; they are just so exciting! Blending modes allow you to apply light properties to a layer that "bleeds" through to a layer or layers beneath it. Your options are truly limitless with blending modes because you can use them in all kinds of different situations and continue to discover new things with them.
If you just have a blank white background layer and try a blending mode on your photographic image layer on top, you're not going to see anything. Try changing that background layer to a bright pink (through color fill methods) and change the top layer to a Color Burn or Overlay. Can you see the difference?
In Photoshop, the blending modes are located on the layers palette, beginning with "Normal". They are set in different groups. The least used one is dissolve (it's just kinda dumb and I think I might have used it once...by accident). The first "set" are your darken blending modes, followed by lightens, light mixers, de-saturaters and color sets. Are these the technical names for the sets? No.
Am I going to technically describe how with blending modes, one layers light qualities are mixed with the qualities of the layer beneath? No. This is Photoshop Design; we're concerned with the practical application. (Maybe after I get my ACE certification I'll cringe at this). But you still need to know an idea of how they work. Even the Dream Team members will say that Ben Willmore and maybe Peter Bauer (of Adobe) are the only ones who truly understand them.
Well your first set of darkens (Darken, Multiply, Linear Burn, Color Burn) will saturate the dark areas of the layers. These blending modes work well on layers that are lighter because if they are too dark it's going to blacken out the image.
The second set (Lighten, Screen, Color Dodge, Linear Dodge) works great when you've got a dark layer on top that you want to hide the dark pixels with a lighter layer beneath it. This has often saved the hassle of having to create a layer mask.
My personal favorites? Overlay does it just about all of the time for most of my desired effects. Second most used is definitely Hard Light. These work great when you want the top layer to look richer with the dark areas below; it brings up the contrast too and more often than not, just looks really cool and works well.
When working on a graphic design in Photoshop you should experiment with the blending modes yourself until you personally get a good feel for what they can do and how they work. When you're working with several different layers, use blending modes to let the light qualities "bleed" together. It's a powerful and effective tool (do I keep saying that or what?!)
On all of my club-style designs I'll use blending modes. Try mixing some sunset photo's together on say, color burn. They are powerful tools and using them could become a trademark of yours too! These images all are using blending modes.
Try mixing two photographs together with some blending modes and you'll be surprised at what you find. Night photography works well with flashes, blurs, colors and lines. Try mixing some 'party' pictures together with blending modes!
More Photoshop: 
