Soldato
I would say that Warcraft II is a good starting point if you're new to RTS's. I played this as my first game in early year 2000. Once you've mastered the humans and orcs, the next game to play would be Age of Empires II. The top-down view changes to isometric and there are more types of units you need to control, plus the numerous available hotkeys makes it more of a two-handed game (mouse + keyboard) than Warcraft II. After that, I personally moved onto Age of Mythology and AOE III which had a similar learning curve. I didn't get to play Warcraft III but I'm not sure whether that was an RTS anyway.