How to be more efficient at drafting (technical drawing)?

I recently started an architectural design cl and since I love drawing, I thought I'd really like this. Well, I do like it, but it takes me forever to do a drawing. And to make matters worse, my teacher doesn't tell us how to things, so I have to figure out how to do stuff and most of the time it isn't the most efficient way. For example, today I had to do a brick layout, which would have been easy because it's only 8" rectangles side by side except there is a 1/2" mortar in between the bricks. So I can't draw a rectangle and divide it by 8, because of the 1/2". Needless to say, I'm still not done the drawing and it's due tomorrow. What are some common mistakes you architects and drafting technologists made when you first started drawing, and how did you fix them?