The main rule with tables it the K.I.S.S method (Keep It Simple Stupid). The main things to watch for are:

1. Colour clashing - Watch that the background, border, text, and outside border colours do not clash 

2. Make sure the writing is not too big - it can make a table unnecessarily large

3. Watch the border size - too chunky borders are ridiculous i.e.

4. For a table merge the top row for an effect like so:

   The current point system for Willow Oaks
   Place	Race	3DE
   1st	25	20