Years ago, I used to be very "into" RTSs. I spent countless weekends and weeknights playing Warcraft, Total Annihilation, Starcraft and tons of lesser known RTSs.
And in most of them, particularly the ones with peons, what seperated the top players from the rest was knowledge of a simple game mechanic: Multiplication of resources. Which translates to - send forces to disrupt the first couple of minutes of production of your enemy and you will win. We're not talking about "rushing". What I'm saying is that if you can eliminate even a couple peons getting gold or whatever the resource in question is very early on, it will put them behind the curve for the rest of the game.
When I played competitively, that was always my strategy too. But as I've gotten older, I don't have the stomach for it. It's just such a shitty tactic that is only remotely interesting when played against other top players and even then, it all usually boils down to who is most successful in pulling it off. So I don't do it.
Which means that when I play top players at say Rise of Legends, I usually lose. RoL is a peon game. So a good player will move in with their starting forces and take out a few peons and then move out. The rest is pretty much written barring a really clever move.
Some people object to "rushing". I don't. I don't personally rush, but I think rushing is a legitimate tactic and a well designed game will allow players to defend against it. In Rise of Legends, you can see how many units the the other guy has built early on. So it's pretty obvious when an unskilled player is about to rush. I had that happen today and wiped the guy out. One defense canon and a bunch of purchased forces from neutrals (the guy didn't realize that units acquired at neutral cities don't count as "built" units so I had more forces than he thought).
Other tactics are still key, always know what your enemy is doing. When someone rushes me, I usually see them gather their force, send them across the map and make sure I have something there to greet them. Unfortunately, true rushers are usually pretty lame. The rush, having failed, means the opponent is doomed and they typically quit right there. I never understand those kinds of players, given the pain to get a game going, why end it in 5 minutes?
But like I said, the most effective strategies are the ones that suck the fun out of the game. I've always loathed the peon mechanic to begin with (no war in history was ever decided by eliminating the civilian population). In some games, top players will take advantage of glitches in the game such as bad unit AI and such. RoL does'nt seem to have that issue at least.
So I'll have to contend myself with being mediocre.