Neck angle is mostly determined by the height and placement of the bridge you plan to use. The Gibson style tune-o-matic usually requires a neck angle because it sits so high. You could also sink the bridge or use a thicker fretboard or a combination of all three. Any strat style bridge which lays low doesn't need a neck angle. There should be enough play in bridge saddles to attain good action.
I copied the neck angle on an LP copy for my last guitar. But didn't use that body style. I made a double cutaway instead with all Gibson style hardware, including 2 HB's. The neck angle was 4 degrees and started about 3" inside the body. You learn from mistakes and I realized that much angle wasn't necessary. I resorted to sinking the bridge into the body to put it in better adjustment range. But if I had used maybe 2 degrees or moved the bridge further back, the bridge lowering wouldn't have been necessary.
Another concern is where you start the angle and where you plan to place the fretboard/bridge. If the angle begins inside the body of the guitar, that area ends up being thinner than the rest of the body and routing a pickup hole too close to the edge can be risky, don't want to remove too much wood. A good plan is to have at least 3 frets inside the edge of the body.
I started with a 2 1/4" X 2 1/4" X 39" mahogany block. Its easy enough to measure from another guitar and copy the dimensions onto the block. The important part is making sure your block is square in the beginning. I initially shaped my neck in a crude fashion, I used a Skilsaw to cut my angles from top and sides, while leaving the back of the neck alone. Then I borrowed a large belt sander and sanded one side smooth using the back as a guide. Then flip it and sand the other side. This is important because you need one square side to go by to ensure you get proper 90 degree angles on all corners. Otherwise your fretboard is not in the same plane as the body.
I found its so much easier to do all this roughing in before assembly to the wings. You can then rout the truss rod slot and use the neck as a template to cut your fretboard. The rest depends on what you consider easiest. You could go as far as installing truss rod, fretboard and fretting before gluing on the body wings. Its easier, for me, to do all this because the back of the neck is still flat and stable. After assembly I found out where to place my bridge from the scale length of the fretboard and shaped the back of the neck to conform with the body.
BTW, welcome to the board!