While I'm teaching my little dude the rules, I constructed some single colour decks that were big on creatures, sorcery cards and Instants but light on artefacts, dual lands and enchantments, just until he gets the hang of the basics before I add the next layer of complexity for him.
Something I've rediscovered during these sessions is just how relaxing the art of deck building can be. Getting the right balance of card types and combos is a remarkably Zen thing to do, and I've got a lot of pleasure just from this, even before any cards hit the table!
For anyone who needs some pointers on this activity, there are some great instructional videos out there. Here's one I enjoyed from the Geek and Sundry crew: