Avoid them BSP leaks!
Here I talk about exporting your maps to Half-Life, and some problems you might encounter along the way. I also give a little bit of troubleshooting advice, where to go if things go wrong, and some fundamental knowledge about leaks.

Tools, communities, tutorials:
J.A.C.K. - https://jack.hlfx.ru/en/main.html
TrenchBroom - https://trenchbroom.github.io/
The Whole Half-Life - https://twhl.info/
My Discord server -   / discord  

TrenchBroom compile config - https://twhl.info/wiki/page/Tutorial%...
VHLT compilers - https://twhl.info/wiki/page/Tools_and...

Matt's Ramblings videos on Quake BSP stuff:
Collision detection -    • BSP Trees: The Magic Behind Collision...   - this is done by HLBSP
PVS -    • Quake's PVS: A hidden gem of renderin...   - this is done by HLVIS
Lightmapping -    • Shedding light on Quake I and II ligh...   - this is done by HLRAD
It's not entirely the same as in Half-Life, but it should give you an idea as to what the compilers actually do, and why they're doing it.

Timestamps:
00:00 - Intro
00:28 - Compiling
01:11 - VHLT
02:29 - Setting up J.A.C.K. with VHLT
03:19 - Setting up TB with VHLT
04:57 - Extra compile parametres
05:43 - Actually compiling the map
06:28 - Troubleshooting
07:56 - Leaks
09:07 - Fixing the leaks
10:20 - Avoiding leaks
10:47 - Conclusion, what's next

Other:
I have a Ko-fi if you wanna throw money at me: https://ko-fi.com/admer456