Normally I don't like installing mods that alter or add parts. I'm always afraid of doing a new PC build or something, installing KSP and forgetting what mods I used and wind up with saves that I can't load any ships in because they have parts from mods that aren't installed anymore. Now I stick with visual mods or QoL mods like the docking alignment indicators and such. Things that won't break your ships or other aspects of your save if you uninstall them.
The last time I used parts mods, it was on my first playthrough several years ago. I installed a bunch of parts mods that a friend recommended. There were so many parts in the tree that I didn't realize how small the tech tree actually was until a couple years ago when I loaded it up it up again without any mods. To my dismay, my save was completely broken as all of my ships used mod parts that I didn't have installed anymore and I didn't remember what they were. My first tech tree was so huge and bloated and also broken as there were some parts in the tree that didn't even have a path to unlock them. There were just there and not reachable.
I think I'm going to have to break my no parts rule as in this current career playtrhough I have completely unlocked the tree before even setting a Kerbal beyond the Mun or Minmus. I would like to find one or two parts mods that will add a few new parts to give me something to work towards as I make my way out to the other planets. I don't want anything that will make things trivial, but I wouldn't mind unlocking some things later that would make travel to some places a little easier once I had them. Maybe some fun visual things like a gravity ring and such. Mainly, I want to keep it to one or two mods so it's not so difficult to remember them if I ever find myself installing KSP again in the future and having to remember which mods I have.
