Like Gigi said, whatever works for you; it just depends on personal preference, as there is no SYSTEM that you should follow. Lately I haven't even been using conditioner because I feel that my hair's weighed down by it. Also, sometimes my hair feels oily by the end of the day (regardless of weather) when I used conditioner the night before. I noticed that my hair feels fuller (maybe even with a bit of volume) and softer when I skip the conditioner. Of course I'm using PM tea tree oil shampoo right now. Sometimes I will use my dove cool moisture shampoo as well, and they're both effective.
My hair DOES get oily if I don't wash it for a day, so I feel it's best to wash it everyday. Washing it twice a day did feel drying for me though, but I did that whenever I went to the beach. I would wash my hair after going to the beach, and then wash my hair again later that night.
QUOTE(AyeVickaye @ Sep 9 2009, 10:06 PM)
Btw is it bad to use 2 in 1 shampoos?
Once again, it depends on personal preference. The great thing about using 2-in-1 is that it's more time-efficient, and the consistency is more like shampoo. So basically you just massage into your scalp and then rinse. I think this is optimally more efficient for people with shorter hair.
However, if you have longer hair, and religiously shampoo and condition your hair in a certain way, it is better to have separate shampoos and conditioners. With longer hair, you really only need to use shampoo on your scalp (remove dirt and oils), but once you rinse it out, the shampoo cleans out excess dirt and oil from the rest of your hair as it runs down your hair (read this in a magazine). Then when you condition, use conditioner a few inches away from your roots. When I do decide to condition, I put most of it on the ends of my hair (the most dry), and just rub the rest upwards. With a separate conditioner, you can control how much conditioner you use (more with longer hair). Also, with dryer hair, you should be leaving the condition in for at least a minute so that it can soak into your hair shaft (or whatever it's called).
Hope this helps. Some of this is from magazines that I've read (which all virtually say the same thing one way or another).