Even as someone who loves TCGs, it's always disappointing to find out a shop only carries them (or miniatures games). Along with just being frustrating for people who might want to buy or play other games, it's usually not healthy for the shop in the long term, unless they have a very strong online sales presence.
The two biggest things to note with the Mind deck are that storm counts spells cast by all players during that turn and that you don't always need to be concerned about getting combat value from your creatures. The Mind deck can easily win without casting any creature above three mana; in fact, it's technically able to kill by turn five, regardless of what the opponent does and without entering combat, by way of the two cost-reduction creatures, burn spells, and the storm mechanic. That said, this would require quite the nut draw, and the deck is far more likely to win via the creatures that generate tokens whenever you cast noncreature spells, the creature-token-generating storm spell Empty the Warrens, or just cheating out the big spells and creatures. It's also worth noting that using Snap to remove a creature during combat can totally blow out an attacking opponent - bouncing Lovisa Coldeyes or a large Rubblebelt Raiders can very easily save your ass, and since Snap lets you untap two lands, it leaves mana open if you've got any other instant-speed spells you want to cast that turn. Later on in the game, if you've got six mana open, you can cast Quicken and then cast the sorcery Temporal Fissure at instant speed, taking advantage of any spells your opponent may have cast during the turn for a higher storm count to bounce more permanents - unlike Snap, Temporal Fissure can bounce things like lands or the very powerful artifact Coat of Arms. Finally, when casting either Snap or Temporal Fissure at any time, note that the many creature tokens your opponent can generate will disappear forever if you bounce them! Despite the set including physical cards to represent various creature tokens, they don't count as cards and can't exist in any zone except the battlefield.
The Might deck is for the most part straightforward aggro, but it's got a few tricks of its own - for example, despite blue being the color of counterspells, the red/green Might deck is the only one of the pair that gets a counterspell of any sort (the one-of Guttural Response, which can blow out many of the Mind deck's strategies for just one mana). It also includes several spells with flashback, so the Mind player will need to pay attention to what the Might player has in their graveyard - even with an empty hand, the Might player can cast Sylvan Might or Beast Attack from their graveyard during combat and run over the Mind player or make a surprise blocker. Finally, just like the Mind deck, the Might deck is capable of winning incredibly fast (unsurprising for an aggro deck, of course), and unlike the Mind deck, it's able to do so somewhat consistently. The deck is capable of getting a large number of creatures out very quickly, and with Lovisa Coldeyes (who gives almost every other creature in the deck a sizable boost and haste) and Coat of Arms (which can win the game on the spot, depending on what creatures you've played so far), the Might player can roll over the Mind player with ease.
A couple of things for both players to note: Coat of Arms affects all creatures, not just its controller's creatures, so if the Mind player controls both of their Goblin Electromancers and the Might player controls Zo-Zu the Punisher, all three Goblins will get +2/+2, and the Mind player can easily benefit quite a bit more from Coat of Arms if they've got one of their token generators out, as each additional token of the same type will boost the others more and more. Also, since the decks share a color, there's some neat customization you can do between the two without having to buy any extra cards - for example, after you've played with the decks a bit, you could try swapping the Mind deck's Volcanic Vision for the Might deck's Beacon of Destruction if you want to go harder on a burn theme in the Mind deck while giving the Might deck a way to deal with the large number of creature tokens the Mind deck can generate, or trade the Mind deck's Young Pyromancers for the Might deck's Burning-Tree Emissary to make the Mind deck's storm gameplan work better while giving the Might deck another way to go wide.