6) Build the "right units", learn what units to make for each type of player. If you see a Night elf player going for Chimaeras and Hippogryphs, then build the correct army and kill the Night elf player. Then figure out your next target and what units to make next. Kill your own unneeded units and then create your next "ideal" army. I have round 5 or 6 "army templates".
I use a different template based on who I'm fighting. It's better to plan your entire army vs. a single player (who should be your largest threat). With the right army + good micro your 80 food army will kill their 100 food army. You will might need to deal with a 2nd army which might be made of units which is a counter to your own army.
Good scouting and a few towers can buy you some time to allow you to switch to the correct units. This is tied back to rules #1 and #2 and predicting who and when you will be attacked. If you are caught off guard by another player then it's your own fault. 7) It's important to adapt. One of the most useful items in FFA games is the tome of retraining, for some reason very few players ever buy this item. I HIGHLY recommend Orc players, who get a Far Seer to switch from Wolves to Far Sight at level 5 or 7 (level 3 Far Sight is perhaps the best spell in the game for FFAs). Dogs are great for creeping, while level 1 Far Sight isn't so great, so at level 5 you can spend 300 gold to switch your spells around. I recommend Human players who go Archmage first to switch from Water Elementals to Blizzard around level 5. You can even switch back and forth based on the army you need to fight. Water Elementals are great for creeping and against players who go all air (or Huntresses), but Blizzard is generally a much better spell
later in the game when you are dealing with 100 food armies. Learn the different maps, and adjust your rules of when you should expand based on the map. Large map games differ from small map games. Learn what works better for your play style and thumbs down the 2 maps you have the most problems with. For me, I like to fast expand and I tend to prefer larger maps. In some games every starting spot has a player, you might want to think about rushing + towering a player next to you. If you can pull it off, you will own more of the map than any other player. 8) ALWAYS scout the two spots next to you at the start of the game before committing to a build order. Its important to know if you have a player right next to you, or even if you have a player on both sides. middle spot is always bad, but if you at least know you have the middle spot you can adjust (you will need a few more towers at your main, and an expansion on the other side of the map + lots of TP scrolls). If you only have
one player next to you, it's helpful to know if that player has someone else on the other side of him (meaning he got the middle spot), in which case you can pretty much ignore that player and hope the guy on the other side of him takes care of you. When you scout your neighbors at the start of the game, be careful not to be seen.
And if you are seen, run the opposite direction and make it look like that is where you came from. You don't want to give away your position, otherwise the player who saw you might be your typical "solo" player. If the player is a solo player, they will likely hero harass you and you will end up fighting them for 20 minutes while everyone else techs.