Most problems are formatted such that each part of them can be written down as equations AS you are reading them. I only find myself needing to reformat occasionally.
For instance (question borrowed from Khan Academy):
As an object's depth below the surface of a body of salt water increases, so does the pressure acting on the object due to atmospheric and water conditions. The rate at which pressure increases
Pressure Rate...
is approximately 11 pounds per square inch (psi)
Pressure Rate = 11 psi...
for every increase in depth of 25 feet (ft).
Pressure Rate = 11 psi / 25 ft
The pressure at
Ok, they're about to give us a value for pressure. Not pressure rate (psi/ft), just pressure (psi). So I think we should derive a new equation where the feet unit is canceled out by a depth of x ft.
Pressure = (11psi / 25ft) * x ft...
The pressure at the surface of the water is 15 psi.
Ooh, not quite the right equation yet. When x=0 (depth is zero at the surface), pressure isn't 0, it's 15. So that needs to be added.
Pressure = (11psi / 25ft) * x ft + 15 psi
Rounded to the nearest foot, at what depth will the pressure acting on the object be 50 psi?
Now they're giving you a value for pressure, 50 psi, to plug into the equation you just built, and hey, look, we're solving for the unknown depth, x.
50 psi = (11 psi / 25 ft) * x ft + 15 psi
By the time I finish reading the problem, I've already written the equation I need to solve it. This works in a fairly linear fashion for nearly every math word problem on the SAT. You may end up having written more than one equation, and then you have some sort of system of equations to solve via elimination or substitution.