I have been known to be pretty creative when doing my planning, so now I shall share a trick I have discovered that I think are pretty ingenious.
If your venue is outdoors, try taking a screenshot of Google Earth, this way you have a to scale image to draw on and map out your venue.
Honestly, I pasted it into paint and did the roughest design ever. You could even print it out, or draw a grid over top to make it to scale.
Spacial planning is incredibly important. If you are working with a space that is going to be tight, you need to maximize your area. Many venues provide floor plans online. Paint, publisher or a pencil, you can make a map and your coordinator will love you for it.