If you understand the basic function, these do not have to be painful.
y = tan(x) does what? It has vertical asymptotes everywhere cos(x) = 0. Draw a few of those. tan(x) = 1 everywhere sin(x) = cos(x). This is at pi/4 and every pi after that. Draw a few of those. It is zero everywhere sin(x) = 0. That's x = 0 and every pi after that. Draw a few of those. You should be seeing the shape of the thing. Sketch a few periods.
y = 2tan(x) This is just a little vertical stretching. Start with the graph previously described. Erase whatever you labled (pi/4,1) and relable it (pi/4,2). You're almost done. Relable a few more things and move on.
y = 2tan(2x) This is just a little horizontal compression. Start with the graph previously described. Erase whatever you labled (pi/4,2) and relable it (pi/8,2). You're almost done. Relable a few more things and move on.