When i play melee games i rush depending on a few things. If its a 1v1 map w/2 spawning points i almost definitely rush. The fact that i rush almost every time is that i always play orc. Human, and Night Elf are also good rushing races, but Undead arent good rushing races. If you are a random player you should creep if you are undead. I've seen some undead builds where when their hero spawns they have 2 fiends 3 gouls and 2 skellitions from the rod of necromancy, but the hero is late thus making it not really much of a rush. Also, a major decision factor when rushing is when you've scouted their base (which you should do ASAP). Basically, rush if it's a good idea to rush, and don't do the same thing every game because one thing is easy to counter as opposed to multiple things. For those of you who are new to the game, you should always ALWAYS rush if they are teching too fast, and you also have to consider your economy when rushing. For example: its always better to town portal instead of loosing a whole bunch of units cuz a tp only costs 350 gold when an army costs a lot more while keeping exp away from your opponent. I noticed that this game differs from starcraft in a way as that your army's survival is key to your survival. Alot of people think that going for buildings and trying to get your opponent to loose from killing all his/her buildings which is a bad idea. So when you rush you basically want to go for peons and other fighting units. The #1 thing when you rush is to not loose any units, your first few units are almost twice as valueable. I also hold the alt key down almost too much cuz it makes HP bars over each unit and you can see where your enemy is focusing and you can keep the focused units out of danger by having them run. Anyways, rushing is good, but dont mess it up because it will hurt you if you do.