About 2 months ago, I installed OpenBSD 6.9 on my thinkpad t450, and I'm going to walk you through how I customized and tuned it.
When I first installed it, the first thing I notice that the backlight keys didn't work (pressing them set backlight down to 0) but no big deal, I just used intel_backlight_fbsd, which works for OpenBSD.
This time around, I didn't need to run fw_update as my laptop was connected via ethernet and so it ran it automatically. When I first booted, I logged in as root, intalled nvim with pkg_add neovim and added the following line to /etc/doas.conf using nvim:
permit persist keepenv will
After editing doas.conf I logged out and logged in as my standard user, then I edited /etc/sysctl.conf and added the following options:
machdep.allowaperture=3 (This is needed for intel_backlight_fbsd to work)
hw.smt=1 (allow hyperthreading support)
Afterwards, I installed git using pkg_add and then cloned my DWM and ST builds, and installed them.
Once I started my graphical environment, I realized that my trackpad wasnt disabled (I'm a trackpoint fan myself) so in /etc/wsconsctl.conf I added the following lines:
mouse.tp.disable=1
mouse.tp.tapping=0
keyboard.bell.volume=0
The first 2 lines disable the Touchpad partly, (Just not the clicks, which is good enough for me.), and the Last line disables the annoying keyboard bell. I then rebooted to apply the effects for sysctl.conf and wsconsctl.conf
I then ran the commands doas rcctl enable apmd (enabling power managment) and doas rcctl set apmd flags -A (Setting apmd to auto adjust the cpu).
Afterwards, I installed the packages nitrogen (For wallpaper management) compton (For compositing/transparency) and xbindkeys (For non-wm keybinds), pulseaudio (For easy audio) and firefox (Web browser)
I then started dbus in my .xsession according to the dbus pkg-readme, logged out and logged back in.
Once I had my window manager and keybinds set up, it was time to configure firefox, I opened about:config and set layers.acceleration.force-enabled and gfx.xrender.enabled to true. Now it was time for the fun part!
After I had the base part set up, I upgraded to -current with sysupgrade -s and then updated my packages with doas pkg_add -u
I now have a buttery smooth firefox and desktop running on OpenBSD 6.9-current! it was a blast and I plan on using this amazing OS for the near future.

Have any questions or comments? Put them below!