Start by drawing out the di-punnett squares to determine the genotypes of the parents and then from that you can readily figure out what the gametes produced from each parent are going to be based on their genotype.
the gamete must contain exactly one from each trait (e.g. you could have three traits marked a,b and c, each having two alleles A,a; B,B; C,c -> then the diploid organism can have any combination e.g. AaBBcc or AABbCC etc., but the gamete has one from each thus e.g. AbC or abc, but not aa or Bb etc.)
