I've often pondered this "tee it forward" business - especially with when I read about recommendations to go forward two tees.
I mostly play public courses (in the U.S.).
For the most part, these courses have Blue tees (all the way back); White tees (which I have always regarded as the men's non-tournament tee); yellow tees (seniors/juniors); Red tees (ladies).
I always play off the white tees, unless I'm in a comp which mandates the blue tees. I'm assuming the white tee is the correct tee for someone of my handicap?
Another English person raised this question earlier this month, as I recall - on most English courses there are only ever three tees: men's tournament (usually white), men's regular tees (usually yellow, so far as I recall), and ladies/juniors (red). When I moved to the US I just started teeing it from the first set of tees forward from the tournament tees - which seemed right, as that's where practically every other male golfer seemed to play from.
But is wrong or old-fashioned to think about tee colors with regard to the characteristics of particular golfers? In other words, should it be yellow tee for anyone whose ability suggests that they should be playing off that tee, rather than yellow tee = kids and seniors (outside of tournaments, of course, when the forward tees are normally restricted to players based upon some sort of age + handicap arithmetic).