I don’t know if I can provide a proper tutorial for making a header, so the least I can do is tell you where I get the images for making them, as well as sites that I get my fonts from, for the header’s text. I mostly get my images from Fotolia.com, because that’s the cheapest place I discovered and they have tons of stocks to choose from, so I almost never run out of choices. When I do, I go to iStockphoto for their royalty-free images, but only when I really can’t find anything suitable on Fotolia.com.
As for the fonts, I mostly go to DaFont.com and Font Space to look for an appropriate font style to match the graphics I have in mind. Designing the mock-up takes up almost as much time as coding, sometimes even longer, because of the amount of minute editing and re-editing that the clients sometimes most of the times require.
I admit I’m unexceptional in conceptualizing the perfect layout, but if there’s anything I can do, I can be patient with clients and give them what they have in mind. I guess that’s what makes me a decent blog designer. Not my artistic skills, as I have little of that, but my people skills. Oookay. I should stop bragging now.