How to Counter The First Boss Lazers
You move constantly, fast, and dodge the beams when facing it while shooting, until you reach cover – maybe for a reload – then mix up the direction in which you go when you get out of cover.
My best run where evidently with higher damage, but also trying to screw with its tracking! I got instantly melted on my first 10 runs, but a bit of practice with new runs – this is not Dark Souls – made all the difference, even without any meta-upgrades (1.0 release wiped all my meta-progress and yet I melted it on my first run after launch).
Hope this helps a bit; someone might have better tips. I just never needed to study it to do fine. I will start analysing it a bit more as I keep playing, to make sure I can kill it without any damage taken early game.