Yeah, what Blizz said. Best thing you could do is start by making lines that go straight across the pattern (Diagonally, Straight, In a wave pattern, whatever, as long as it ends up starting where it finished on the other side). Or, if your Fill tool supports it, switch from Fill All (Or whatever it says in whatever program you're using) to something like "Lines" or whatever. Then it'll make all those lines for you.
This might be a bit complicated, maybe picture tutorials would help.