Use a softer wood (like pine) so that when you nail it goes in with ease and doesn't split the wood too easily!
Before you begin nailing tape on your design and prehole your marks using an ice pick. This will allow you to pull the paper off before you begin nailing so that little pieces of paper don't get stuck under your nails!
Here is a picture of some of the basics I like to use!
Hammer the nails in far enough (about half way) so that when you pull string around it the nails don't pull out or loose shape.
Hot glue the ends of your string with a small dab of glue so that the knots do not pull out easily!
Be careful not to hammer all the way through the wood!
Don't hammer your fingers holding the nails! (I know this seems silly to mention but yet its so easy to do!!) I like to hold my nail with small needle nose plyers so that my fingers are more back and less likely to get hit!
Don't wiggle the nails too much once they are in the board as it will make the hole larger and compromise the integrity of the hold. If you don't like the nail how it is just pull it up and out as smooth as possible.
Don't use a hard wood!! (Yes I know I'm being redundant here from the Dos section!) If you don't get a soft enough wood it will make your project a nightmare! Not to mention your nails will be more difficult to get straight and in far enough.
Don't nail too close to the edge of your wood as it could easily split your wood. The more nails that are in a line following the grain of the wood, the more likely you can split the wood so be aware!
This example shows how close I put the nails along the bottom edge of the board and my wood cracked a bit! I had to use wood glue and clamp the wood along the whole project to get the wood to stick back together again and hold the nails in!
Don't nail over a knot in the wood! The knots are extremely hard to nail into and can compromise your wood integrity if not careful!