I've been asked a few times how I create my photo collages and until now I haven't bothered posting a tutorial because it seemed that my software of choice, a little-known program called PhotoImpact X3, had been discontinued. However, it appears to be available again - and for the bargain price of $19.99, what's more - so here goes!
PhotoImpact actually makes it incredibly easy to make effective digital collages. It's almost a cross between photo editing and desktop publishing software. Unlike in Adobe Photoshop (which I'm not very experienced in at all), every object can be manipulated individually, without any need to worry about 'layers' and so forth.
Gather your digital materials
First, prepare your photo(s). I usually use Picnik.com because I like the effects it offers, but PhotoImpact does have some cool effects of its own, including "diffuse glow" and "add vignette", as well as preset sepia tones.
Next, like a real-life collage, you'll need some ephemera to go with your photos. I use scanned ephemera (postcards, book pages, sheet music, button cards, photo wallets etc.) both from my own collection and from Flickr. A flickr search for "cabinet card", for example, will bring up hundreds of Victorian photographs with attractive mounts, which I use in most of my collages.
Create the collage
In PhotoImpact, create a new blank image, which will be the base canvas. Copy and paste your photograph, or drag-and-drop directly from Windows Explorer.
Making a cabinet card mount
Use the Path Drawing Tool (1) to draw a rounded rectangular (2) around the cabinet card. Set the mode to Selection (3) and adjust the corner roundness to match in the Tool Settings box on the right.
Copy and paste the cabinet card into your collage. You'll see that as you add objects, each can be controlled individually; you can use the pointer tool to arrange the layers (bring forward, send backward, etc.).
The card probably won't be exactly the right size and shape to mat your photo, but it can be resized to fit with the Transform Tool - make sure the aspect ratio is unlocked (but when you're resizing your photo make sure it's locked, otherwise you'll end up stretching the picture out of proportion - never a good look!).
At this point I usually add a shadow to the cabinet card (to add a shadow just right-click on the object and go to "Shadow"), before 'grouping' it with the photo (select two or more objects, right-click, 'Group') so that they can easily be selected and manipulated together.
Building up the collage
You can see the collage taking shape now - I've added some ephemera saved from flickr, and used the Transform tool to rotate both elements slightly for that 'casually tossed' look.
For irregular shaped items on a plain background - like these flowers - you can use the Magic Wand Tool to select the white space around it (including between the leaves by using the Magic Wand in 'addition' mode, which adds to the exisiting selection each time you click), then invert the selection (on the Selection menu) so that only the flowers are selected.
The flowers can then be inserted and into the collage and layered with the other elements, and hey presto, a simple but effective collage!
Yes, it's really that easy - I use very few fancy techniques. In fact I've probably just ruined half the mystique of my blog!
Anyway, I hope this was helpful - if you have any further questions or would like me to explain any more techniques in more detail please let me know and I'll do my best to help.