Modelling for a game engine, stuff I should know? Good evening. I would like some help, if someone would be willing to tell me for what I should watch out and what I should know when I make a model for any kind of game Engine.

I do know I have to keep the model as simple as Its possible (poly count) and to use Normal maps to add complexion (...)

I remember that game engines see the structure of a model in triangles, Should I learn how to model in a triangles? or does Blender have build in conversion. I remember once hearing about other software that can convert a model while keeping the same structure,complexion, from quads to triangles (i don't think thats the proper way of saying it)

Any help would be nice, point me to a video, text or you can explain here.

Thank you for reading.
Unless you tell us what game engine you're aiming for, it will be hard to be specific.

However, you shouldn't try modelling with tris, it would be hard and pointless. With triangles you can't use loops, most tools won't work as intended (ie. Bevel, Inset...) 

Either let the engine do the conversion (Unity, UE4, Godot, does it really well) ; or if you want more control, handle it yourself just before export (ie, Blender "Triangulate" modifier)