Henk,
My main point is that I don't really think its possible to teach how to do a clever design. The only solution is to build up to it the hard way, by practice. No amount of tutorials can teach how to make the intuitive leap to the brilliant, simple, low cost or whatver selection criterion you choose to decide is the best fit to your ideal.

Steve

PS I don't think I have ever claimed to be called an expert. It is an honour to have had that designation awarded by other participants in this forum.