There is nothing wrong with 2. D4. Having both the E-file and D-file pawns up at the same time is one of the most basic examples of excellent central. Your opponent most likely will go into what I think is called the "Modern Defense" (correct me if I'm wrong), which is 2. Bg6. 3. Nf3 should defend the D-file pawn from black's G-file bishop.
If you don't like using 2. D4, 2. Nf3 is also an acceptable means of grabbing central control. There's also 2. C4, which I'm not a fan of, I prefer 2. Nf3 over that.
After 1. e4 g6, I don't know what to do. Sometimes I try this: