More Complexity

You can have two or three traits going on at the same time. 

all you need to do is either create gametes and do a big chart

or cross the two traits separately and multiply each combination. 

both ways work, but I personally prefer separating traits and multiplying because it's fast and you can choose to only determine a couple of phenotypes. for the big chart it's necessary to finish the chart, which sometimes gives you excess information.