I played a large amount of DotA over the new year holiday, shortly after I started recording my self-advice. So within a day or so, the list had expanded quite a bit.
At this point, I was still playing exclusively Limited Heroes matches.
* Facing multiple invisible heroes? In base with a spare inventory slot? Put dust or sentries or something in that slot, every time. There's a good chance it makes the difference between a kill and a survive, and if I don't end up needing it before the slot I can hand it to a teammate and look generous.
* Do not hang out alone right outside the enemy base. Especially if I don't know where any of them are.
* Just bought an item with an active fighting ability? Make sure I know what button it's hotkeyed to before picking a fight.
* Similarly, always put my 'use when you panic' item on Z - salve, magic stick, mekanism or w.e., in a panic situation any plan more complex than "hit Z to not die" is too slow. "Mash all the item hotkeys twice" is definitely too slow.
* Even if the courier is dead, it isn't necessary to buy a second one.
** If my team has two couriers, make sure I use the upgraded one. It's less likely to die.
*** If someone insists on using the superfluous, unupgraded courier, upgrade it myself so that it doesn't die.
* Ring of Aquila is a fine item. 2 Rings of Aquila is too many though.
** Disassemble the Aquila before buying Vlads, instead of selling. It saves money for exactly the same effect.
* Do not hang out alone right outside the enemy base. Especially if I don't know where any of them are.
* Just bought an item with an active fighting ability? Make sure I know what button it's hotkeyed to before picking a fight.
* Similarly, always put my 'use when you panic' item on Z - salve, magic stick, mekanism or w.e., in a panic situation any plan more complex than "hit Z to not die" is too slow. "Mash all the item hotkeys twice" is definitely too slow.
* Even if the courier is dead, it isn't necessary to buy a second one.
** If my team has two couriers, make sure I use the upgraded one. It's less likely to die.
*** If someone insists on using the superfluous, unupgraded courier, upgrade it myself so that it doesn't die.
* Ring of Aquila is a fine item. 2 Rings of Aquila is too many though.
** Disassemble the Aquila before buying Vlads, instead of selling. It saves money for exactly the same effect.
A few days later, I put together another list after developing a bit of map awareness.
* Playing an invis hero? I can check whether someone has detection in their inventory by left-clicking them.
* Be careful about calling couriers to a pushed side-lane, especially before the upgrade and especially if I don't have the jungle warded at all. It's better to meet the courier at the tower than to lose it to an observant support.
* Pulling when the creep wave is already at my tower is an easy way to lose a tower.
** This mainly applies to a solo lane. In a dual lane the other guy can handle the creep wave.
* Do not ignore Razor's link.
** Do not stand near Razor after my lane-mate ignores his link.
* Most heroes can jungle starting at about level 10. It may not be very efficient, but it's a safe way to finish a major item.
* Arcane boots may not be available at the base, but they are available at the side lane shops.
* Killing a creep while someone is trying to Boots of Travel to it cancels the teleport. Attempting to warp to a low health creep is risky.
* Attempting to 1v5 or even 1v3 is almost always a bad idea. Exceptions: If I can reduce it to a 1v2 or better inside 2 seconds (late game) or am under a friendly tower (early game) it might not be a bad idea.