I don't know what you consider good technique (Bit and pieces tend to vary by individuals and situations). So I'll throw out a couple things to think about.
First, lower areas tend to have grittier dirt than upper areas. In addition to this, upper areas tend to show scratches and marring worse than lower areas. If your paint is soft or dark, it might be worth your time to make up to three passes on the vertical areas of your car. Once, at the very beginning of the wash, I would hit all paint to under body edges. I personally do this with a hand pump sprayer and a brush. The hand pump sprayer is going continuously as I brush the edges to wash/aggitate/rinseaway debris. Next, start the regular wash - top down. Except, instead of washing vertical areas top to bottom, make two passes - top to lower mid and mid to bottom. Do all the top to lower mids first and than go around again and do all the mid to lowers next.

One, more thing. Try using a soft sponge (I use one of the Optimum ones). It's worked better for me.