use bevels man and work in all quads. It's the only way to get decent results. The idea is pretty simple. when smoothing out a lowpoly mesh, anywhere that has a quick interpolation between one angle to the other, or a hard angle into a smooth curve you need geometry to support that transition. this image isn't perfect by…
Nah this is not a prob with smoothing groups. You have a six sided polygon because of those edges coming from the chamfer towards the top are ending abruptly. Follow them thru to the bottom of the model and you should be straight.