Sudoku and minesweeper can be solved without guessing. The reasoning they share, two ways to scan sudoku, overlapping numbers and what to do when stuck.
Sudoku and minesweeper look different but do the same work. You hold a set of candidates for each square and eliminate the impossible ones using the given constraints. When one candidate remains, the square is settled, and settled squares shrink the candidates elsewhere. That chain is what drives the solve. That is why the elimination habit learned in one puzzle carries over almost unchanged to other logic puzzles.
You can work from the square or from the number. When one direction stalls, the other often opens it up. Start by sticking to one viewpoint, and get into the habit of switching to the other the moment you stall.
A number tells you how many mines sit among the eight surrounding squares. Two certainties follow. If the number equals the count of closed neighbours, all of them are mines; if the flags already placed equal the number, every remaining closed neighbour is safe. Those two rules alone resolve a large share of any board. When the first click opens a wide area, working through the numbers along its edge in order is the most efficient start.
When a single number is not enough, look at squares shared by two adjacent numbers. If a one and a two are adjacent and share squares, you can work out whether the mine already accounted for by the one is also counted by the two, and settle the rest. Most intermediate situations resolve through this overlap. Sketching the two numbers and their shared cells on paper at first makes this way of thinking familiar quickly.
Minesweeper can end with too little information, leaving a probabilistic choice. There, counting remaining mines against remaining closed squares and taking the lower-probability option is the best available move. A well-made sudoku, by contrast, has a unique answer reachable by logic alone, so needing to guess usually means a clue was missed. Even when forced to guess, choosing a cell that will reveal plenty of new information if it is safe is better for what follows than an information-poor edge or corner.
Getting stuck usually means there is an unused clue on the board that you are not seeing. Rather than staring at the same spot, sweeping the whole board again in a fixed order brings the missed clue to light: in sudoku, once for each digit from 1 to 9; in minesweeper, number by number along the edge of the opened area. A mechanical sweep is often faster than intuition.
Sudoku difficulty is set less by how many digits are given at the start than by what level of technique is needed to solve it. An easy puzzle can be finished with simple single-candidate placements alone; a hard one only opens up when you weigh candidate relationships across several cells at once. In minesweeper, board size and mine density set the difficulty: the denser the mines, the more often you need to combine two numbers, and the more often you are forced to choose by probability.
Puzzle skill grows less from volume than from revisiting where you got stuck. If there was a cell where you paused for a long time, check after finishing which clue settled it; that type of clue will jump out at you next time. In minesweeper, aiming to finish without guessing rather than aiming for speed builds logical patterns quickly. Practising flawless solves one level below your usual difficulty is also more effective than it sounds.