So, whenever a land enters the battlefield under our control we must (not may) draw a card. She is an incredible value engine, in one of the best color combinations of Commander, even though her mana cost (5 cmc) can be considered a little high.
I believe that in order to get the fullest from her abilities we don't have to play endless ramp spells or stuff the deck with 50 lands like Azusa, Lost but Seeking. Here's the decklist.
The plan of the deck is to use cards like Stasis, Sunder, Mana Breach and Storm Cauldron to mess with the opponents' board states while we use cards like Seedborn Muse, Exploration, Walking Atlas and Wayward Swordtooth in order to break parity and advance. There are several wincons: Use Retreat to Coralhelm with Cloudstone Curio and a creature like Walking Atlas or Llanowar Scout to draw your deck, if Tatyova is in play, and win with Labman or Jace. Alternatively you can bounce Sunscorched Desert to damage opponents or use Words of Wind for mass bounces or an arbitrarily big Hurricane.
I have found that you shouldn't play Tatyova immediately on turn 5, unless you have some form of protection or you are already far ahead with ramp spells. Our commander is rather best in few explosive turns than with a continuous board presence. Most of the time she draws removal like magnet and the counterspells are there to protect the winning pieces.
Ramp spells are useful both in early game for... ramp and later when Tatyova is online as cantrips. Splendid Reclamation and Crucible of Worlds protect from MLD and are used for value interactions with Trade Routes and Sunder discards. We also have some tutors to search for creatures that provide the extra land drops.
Cards I'm not sure that are useful yet or haven't appeared much during gameplay:
Ertai, Wizard Adept: is a cute interaction with Seedborn Muse but it also baits much removal
Kruphix, God of Horizons: helps store unused mana and powers game-winning Hurricane and Blue Sun's Zenith
Teferi, mage of Zhalfir: protects on the winning turn, still not sure if the mana investment is worth it.
Cards that I want to test or not currently own:
Amulet of Vigor: This is on the top of my list because it allows lands from Splendid Reclamation to come in untapped and also generates infinite mana with Simic Growth Chamber bounces. This will also make me want to put Scapeshift in the Deck.
Root Maze: Makes opponents sad and is a great combination with Amulet of Vigor
Winter Orb, Overburden: More stax might be good
Turnabout, High Tide, Argothian Elder, Quirion Ranger and friends. All these cards provide more mana and the ranger helps with Tatyova's ability.
Ghost Town, Strip Mine, Oboro, Palace in the Clouds and other utility lands are neat. I haven't got around in ordering them yet.