Everyone strives to find the look they really like. It really isn't that easy. Skins will look so different depending on the shape you have. A horrible shape can make the skin look horrible no matter how expensive it is. I have gone thru many different shapes and skins since i started here and it is only 3 months. I also spent a lot of time trying demos of shapes and skins. Not an easy process and I would save the ones I like and then compare them to others.
The look I have right now I really love and I ended up with a shape I found for free (that I tweaked) and a skin that cost me 700L and it is from a line that isn't really that popular. Go figure! I do have skins from the more popular ones and they are great skins, but when I found this one, I knew I finally had the look I wanted. It just gave me the extra thing I was looking for and I can't quit put my finger on it. You just have to keep experimenting and trying things.
I really think a person evolves into their avatar as you really have no idea exactly what you want when you first start. But eventually it will click. I did try not to spend too much money in the beginning on clothing until I knew the kind of things I really wanted to wears. My look is very different from what I started with that is for sure!
Edited to add: as pointed out by a previous poster lighting can make a big diference in how you look. Play around with windlights. Makes a big difference.