How to repair "broken" meshes?

Hello Community :cool:
Thats my first post, and i got only 1 year expirence with Blender.
I got a problem in Blender:
If i modell a mesh with boolean modifiers and stuff the mesh gets crasy. The vertices are not clean triangles :mad:
You will know what i mean by watching the screenshots. I cant work with broken meshes :ba:

Manually add the cuts where you want them
Look into X / Limited Dissolve
Connect two verts and shortcut J to connect them
Knife tool is shortcut K

Also try subdividing the base mesh a couple of times before using the boolean so you get a cleaner finished mesh. You can also clean up afterwards in required.

Thanks ! , i already know that with the knife but connecting the vertices with j is new for me. :rolleyes: