Order Within Each Suit
Cards rank A, K, Q, J, 10, 9, 8, 7, 6, 5, 4, 3, 2 from highest to lowest. There are no jokers in this version. A higher card beats a lower card of the same suit, but comparing rank alone is not enough when the two cards have different suits.
Trump and the Led Suit
Spades are always trump. You must follow the led suit if you have it, including during the stock phase. If you are void, you may play another suit or trump with a spade. A legal 2 of spades beats an ace of hearts. With no trump played, the led suit wins: a discarded ace of clubs cannot beat a led 7 of diamonds.
Leading and Choosing Winners
You cannot lead a spade before spades are broken unless your hand contains only spades. When both cards are spades, the higher spade wins. For example, a 9 of spades beats a 4 of spades. Use the lowest card that achieves your goal so you preserve stronger winners, and reconsider your plan after drawing new cards.