In contrast to large team games, winning a 3v3 as the bottom player in the lobby requires pulling some weight. While my opponents dealt me an easy hand by essentially deciding to ignore me and 3v2 my teammates during the opening stages, I still had to claim, exploit and defend about a quarter of the map with a minimum level of proficiency. So while the last set of lessons learned came from a game where I could point to activity that somehow contributed to the enemy surrendering, in this game I can directly connect the victory to the things I did better than someone on the other team.

But first, did I actually learn what I said I did from yesterday's game? I did better at not totally forgetting groups of units; I only "lost" one recluse that way. (I did leave a few Venoms in the back after the minute 12 deep raid, but that was a reasonable precaution, and while I forgot about my rearward-expanding Weaver for a while, I brought it back into action after the raid) I dealt with the same rough terrain by bringing spiders rather than rovers. My commander stayed somewhat active in an important eco role. And I didn't give any stupid area guard orders. And, following chaplol's advice, I placed my factory forward at my section of the front to promptly control it, which turned out to be a near-game-winning advantage over my lane opponent whose factory was very far from the front!

But learning from last time doesn't mean I didn't make major errors! Lessons learned:
1) Start building my initial mex first, then drop my factory. I wasted a bit of valuable first-minute metal by walking my commander away from a mex to drop the factory.
2) If I don't know what's going on after my initial scouting, it means I should scout harder, not get paranoid about cheese. I was playing entirely too defensively for the first five minutes given my lack of visible opposition.
3) Don't be greedy when gridding, leave a margin for error. My wind gen lines had tiny gaps in them because I tried to stretch them to the limit. Fortunately, Myopic noticed and filled in the important ones in the rear.
4) Pushing units up to just out of Stinger range is fine for enforcing a stalemate, but I need to back off and make a buffer before doing actual combat maneuvering or my units might stray into range.
5) My lack of a forward Weaver greatly hampered me. While I didn't want to risk my commander grabbing the border mexes, building a few frontline turrets or automatically repairing my army, I could have risked a Weaver doing all that and would have profited from all three.
6) I wasn't doing a good job exploiting my territory gains due to lack of overdrive. That's because my commander was doing most of the eco work. Again, a Weaver should have been tasked with local gridding - I had plenty to spare at the factory. I was just starting to try to correct this at the end of the game.
7) I did not adjust my factory queue during the game, except for stopping Flea production. While my opponents never really stopped me from mainlining Venom-Recluse, I should've gradually increased production of Venoms which I was losing more often and decreased production of Weavers which I wasn't losing at all.
8) Pay attention to team chat! When a teammate says something like "time to end the game", I should try to support his attack if I can.