This is about a cement pavers patio.
On the figure below the yellow arrows show how the lot is graded
For grading the patio I seem to have two options:
-along the blue lines
-along the red line
Which gading direction is recommended? Bigger picture here: https://i.sstatic.net/GSmHh.png
Blue, or blueish-purple (ie, at a slight angle so it's away from both the house and garage, but closer to blue.) You want to get the water away from the building, not funnel it alongside the building.
Responding to comment: developing a grade is a "simple-yet-tedious" process, for the most part. My preferred method is to set some stakes 3-4 feet tall, mark them all with a level (laser these days, dumpy or transit or water or... in the past), and then mark a line on each, depending where it is, at some fixed distance above the desired grade - say 30" above. Then I run strings, tightly, between those marks, and mark my rake and/or tamper handle at 30" - it's then a simple matter to line up the strings (to form a plane floating 30" above grade) and see if the rake or tamper is too high (mark above) too low (mark below) or right on (mark even with) when set on the surface at any given spot. For convenience the plane should not be too low (or it's a lot of bending to see if things line up) nor too high (it's difficult to get stakes well-anchored for a taught string when the string is 5 feet up the stake.)
You could set something to screed on by adapting the same method - I don't recommend screeding for a sand base - it needs to be well compacted, or it will shift, so screeding it doesn't really do anything much to develop the base you need, IME.
In either case "sloping two ways" is a simple operation of referencing an imaginary LEVEL plane & subtracting for the position in both X and Y before making the mark on the post or setting the plank, pipe, or whatever you'd be using to guide your screed on the non-level plane you are creating.
For a concrete example, suppose we slope 1/8" per foot in blue and 1/32" per foot on red. The high corner is where the garage and house meet. The outside corner by the garage is dropped 1.83 inches. The house side of the end away from the garage is dropped 1.09 inches, and the outside corner at that end is dropped 1.09 + 1.83 inches. Any spot in the middle can have a precise elevation computed, and then you do your best to approximate that in practice, and don't sweat 0.05" too much. For the sake of simplicity and sanity in measuring you can set your grade stakes on an 8 foot grid, for instance, rather than "right at the edge of the patio" and you can actually set a row beyond that if it makes it easier to "see the plane" while working.
