Look closely at the border of your Base Set cards
#3: Each group has a creative identity Most often the factions will have names
Pick Enclave and see how many cards theyre willing to Mill
Market value is $25, and seems fairly stable right now as well, albeit the foil version fetches 10x that, with listings up to $250 at TCGPlayer right now

Abzan Banner Abzan Monument Acidic Dagger Aeolipile Aerial Toastmaster Aether Spellbomb Aetherjacket Agent's Toolkit Alchemist's Vial All-Fates Scroll Altar of the Wretched Amulet of Quoz Ancestral Carvings Anchovy & Banana Pizza Apocalypse Chime Arcade Cabinet Arcane Spyglass Arcbound Ravager Ark of Blight Armillary Sphere Ashad, the Lone Cyberman Ashnod's Coupon Ashnod's Transmogrant Astrolabe Azorius Cluestone Azorius Locket Bag of Devouring Bag of Holding Bagel and Schmear Balm of Restoration Barbed Sextant Barrels of Blasting Jelly Barrin's Codex Basilica Skullbomb Bear Trap Black Lotus Blasting Station Blitzball Blood Fountain Blood Servitor Bloodtallow Candle Booby Trap Boom Box Boros Cluestone Boros Locket Bosh, Iron Golem Bottle of Suleiman Braidwood Sextant Brainstone Breya's Apprentice Breya, Etherium Shaper Bronze Calendar Broodheart Engine Bumbleflower's Sharepot Buried Treasure C.A.M.P

The nine different Energy card types are Fairy, Grass, Fire, Water, Lightning, Psychic, Fighting, Darkness, and Metal