Another trick is to not take your pins out until they are almost under the pressure foot...really close to but not under the needle...the farther out you take the pins, the more the machine can offset the seams.
I usually place my pins perpendicular to the seam I'm sewing so the heads are to the right, making them easier to pull out...when I'm concentrating on keeping my seams lined up, I often put a pin parallel to the new seam but to the left of the pressure foot so I don't have to take it out when sewing...it seems to help keep the butted/crossing seams together better. Make sense?