Self portrait blarrghghgksdfj! I used photoshop and a trusty-ole mirror. I'm a big believer that before you can create crazy awesome mind-bending work from your imagination, you need to be able to hone your observational skills. I don't like taking pictures of myself so I'm not going to upload one so you can compare but I worked really hard on the likeness for this so you'll have to take my word for it that it does look like me xD
This is kind of what I started out with before I began putting in a lot of details. This is a technique that my CG teacher taught us. Basically what I'm doing is I'm putting down the base value first and really making sure I'm getting the values right before I worry about anything like blending and making it look "real." By blocking in the values like this, I also prevent myself from making things to blendy and soft-looking later. Many beginners have the problem with their paintings where it feels like we're viewing the painting through a blurry lens. Soft and hard edges are very important!!!
So this is what my layers look like in photoshop. 1 for the base values, detail blending on face, detail blending on hair and my glasses. There's a couple of other layers not shown for my palette, and some safety duplicates of the layers and the background but yeah! Hope you like it :)