I'll build a model and check alignments by eye and maybe with measurements if in doubt. I am taking much more time with wing incidence and horizontal stab than before. Then with the empty airframe I add a penny or two to the nose until balance starts getting to the planned location. It can be very different for each plane. Biplanes require some careful measurement and is the average between the two wings in proportion to their size.
Once things look right and balance is close I give it a moderate push across the room. If it floats along slows, stalls and drops it needs more nose weight. If it drops nose down it can be nose heavy or may just need up elevator.
Make one adjustment at a time.
A fall off to one side can be a warped wing or uneven incidence. A definite turn left or right needs rudder adjustment.
Once it glides gently on a steady line, then try it outdoors over a lawn with a bigger toss. Once that goes well mark the CG and take notes on all trimming and positions of surfaces.
Then load up the electronics, attach controls and verify CG is still where it should be. Now with the radio on give it a glide test and adjust CG or elevator until you get a fair glide. It will be steeper now but there shouldn't be a turn or stall.
Now try a power up test ready to adjust the trim to get a straight flight. Often on the first flights I only use the trim.
After you land take a look at the trim and adjust the rudder on the plane so the trim can be neutral.
If the plane refuses to climb adjust the elevator with a pinch, or reset the elevator.
If the plane climbs too much with power, reduce the wing incidence or put in more down thrust.
Ideally you will adjust the model airplane with all the controls at neutral. You don't want to adjust your radio and flying everytime you change to a different plane.
Because these models are so light and rugged you can survive all this learning and still have a plane that will fly for years.