Try 50/50, 25/75, and 75/25 blends to start. Do a double-blind. You blend them, label them 1, 2, and 3 and cover the labels. A friend, reorders the wines and labels them A, B, and C, again, covering the labels.
Taste and rank them best to least, then uncover the labels. This avoids unconscious bias.
Plus, it's fun!