I’m attempting to model extremely low poly models right now (like, Quake low poly). I’m trying to use triangles, because using quads makes me run in to problems like this:

Obviously, I already tried to convert that face in to triangles using the F key, but the result was the exact same. 2 of the lines weren’t actually affecting the model. The front one, and the back one were working fine, though. So, how do I convert quads in to triangles properly? Should I just begin modeling with triangles right away? If so, how would I start when modeling with triangles (making individual vertices, and then connecting them works, but takes very long)?

Thanks in advance.