Osmosis is an unusual game due to its foundation rule, where playable ranks “sift down” from higher foundations to lower ones. There isn’t too much room for strategy, but you’ll be kept busy keeping track of which cards can be played to which foundations. Expect to win around one game in ten or a bit more, if you’re good at paying attention.
The top foundation is special because there is no other foundation above it: you may play any card to it (if the card is of the correct suit).
If a foundation is empty, you may start it with a card of any suit you choose provided the suit hasn’t been played to any other foundation yet. The card’s rank must still obey the osmosis rule.
As a convenience, Solitaire Till Dawn X will allow you to change the order of the cards in each foundation if you wish. It may help you, for example, to keep the foundations in King-to-Ace order to make it easier to see which ranks have already been played. But it’s entirely up to you; the order of the cards within the foundations has nothing to do with the rules or with winning the game.
One trick that might be useful is to avoid playing three cards in a row from the discard pile. This helps ensure that you will see at least some different cards on your next trip through the deck.