Sasaya is tricky to build and takes some time to learn how to play. Once you get her working though, she's incredibly fun to play. The deck plays basically like a combo deck, except that the pieces you're assembling are seven lands in your hand. "Going off" is usually Genesis Wave for a huge number, Hydra Broodmaster creating massive hydras, Hurricane and Squall Line one-shotting people, and so on.
The deck doesn't use many of the usual ramp cards; effects that bring lands to my hand are much better than lands on the field, since once I flip Sasaya, I have more mana than normal ramping gets you. Planar Portal and Ring of Three Wishes are excellent for finding Genesis Wave. Helix Pinnacle is likely a noteworthy exclusion; I've never once won with it and always died because it forces the entire table to work together to kill you.
I need to take the time to try and format this into the beginnings of a primer, but here is a post I made on a reddit post regarding Sasaya. It explains a lot of my thought process as far as playstyle and deck construction, and includes sample hands and goldfished example games: https://www.reddit.com/r/EDH/comments/46rlxd/thought_process_for_sasaya/d07etbe
Some more commentary: https://www.reddit.com/r/EDH/comments/573wh6/sasaya_building_questions/d8px68u
Even more commentary (I really need to write a primer): https://www.reddit.com/r/EDH/comments/5ki7f4/any_advice_on_this_sasaya_list/dbo7mnp/
More commentary (man I should really write a primer): https://www.reddit.com/r/EDH/comments/6hia9a/deck_help_sasaya_orochi_ascendant/dj0fro2/
More commentary, including a detailed thought process for my gameplan: https://www.reddit.com/r/EDH/comments/76zcgs/sasaya_orochi_ascendant_thoughts/
Now, when I say combo deck, I do mean it. The deck sits there, quietly accumulating lands, before suddenly exploding and either winning in one massive play or meeting a counterspell. It's a very glass cannon build, but as I explained in some of the discussions linked above, I feel that Sasaya just has that problem innately, so I embraced it. The short version: Yes, green is good at getting lands to hand, but you need seven, so that's a lot of time not actively building your board. Once you get all that mana, people will react appropriately and try to stop you. The deck does nothing without Sasaya, so minimizing potential disruption is key; this includes making your massive play but not winning and having to pass the turn, that's just asking to get dismantled by a board wipe or spot removal.
Used to use land-to-hand-on-ETB creatures; they were initially put in as chump blockers because I took a lot of shots in early game due to being wide open, but now my card selection and land fetching is be good enough that I don't need them.
Add: Fountainport Bell, Keys to the House, Go Forth