1.Nf3 f6 2.Nd4 Nh6 3.g4 c6

White has several options here. Maybe the best choices are 4.d3 and 4.Nc3.

Other moves are:

4.e4 e5 (4...Qa5 is better) 5.Nf5 Nxf5 6.d4 Qb6 (or 6...d5 7.c3) 7.b4 d5 8.exd5,

4.c3 e5 5.Nf5 Nxg4 6.e4 (or 4...e6 5.Bg2 d5).