Hey man, one idea about the helmet.. at the bottom edges your not goin to get it rounded unless it curves back inwards.. so extrude the faces, bring them down a bit, and a bit inwards, extrude again and bring inwards, then extrude again and bring upwards and inwards again.. it should give you a curve like this.

\_/ and will look really nice when smoothed!

The model is coming along quite nicely . You may want to attempt poly cube modelling at one point of time, it works really well . Keep it up and i will be watching!