Where the points are
Algebra and Advanced Math are about 70 percent of the section between them, which is roughly 30 of the 44 questions. Geometry and Trigonometry is about 15 percent, roughly 7 questions. If you have limited study time, that ratio tells you where to put it.
Within Algebra, linear equations, linear functions, and systems are the workhorses. Within Advanced Math, quadratics, exponentials, and equivalent expressions carry most of the weight.
The graphs of the two linear equations in a system are shown as lines ℓ and k in the xy-plane. What is the solution (x, y) to the system?
Pacing across two modules
You have about 95 seconds per question. That is generous for the first several and tight for the last few, because questions inside a module are not strictly ordered by difficulty the way people expect.
Do a first pass where you answer everything you can do in under 90 seconds, flag anything else, and keep moving. Then come back. Finishing a module with three flagged questions and ten minutes left is a much better position than reaching question 18 with two minutes left.
Module 1 sets your routing, so the first pass discipline matters most there. Never leave a Module 1 question blank when the clock is running out.
Grid-ins
About a quarter of the section, so roughly 11 questions, are student produced response. You type the answer instead of choosing it. The rules are worth knowing cold, because a correct answer entered wrong scores zero.
Negative answers are allowed. Fractions are allowed and do not need to be reduced. Decimals are allowed, and if a decimal does not fit the box you truncate or round at the last digit rather than rounding early. Do not enter symbols like the percent sign, a comma in a large number, or a dollar sign. If a question has more than one correct answer, enter only one.
Because there are no answer choices, backsolving and plugging in the options do not work on grid-ins. You need the actual method, which is one reason grid-ins tend to take longer than the multiple choice questions around them.
Using Desmos well
Graph the system instead of solving it. Typing two equations and clicking the intersection gives you the answer with no algebra and no sign errors. The same move handles most questions about where two functions are equal.
Read features off the graph. Roots, the vertex, the y intercept, and the number of real solutions are all visible once the function is plotted, which means you do not need the quadratic formula or the vertex formula on many questions.
Use a slider for unknown constants. If a question asks for the value of k that makes something true, define k with a slider and watch the graph change. That turns an abstract question into a visual one. The limit of all this is time, though. Typing a complicated expression correctly takes real seconds, and a typo produces a confident wrong answer. If the algebra is two quick lines, do the algebra.
The mistakes that cost the most
Answering the wrong question. The SAT regularly solves for x and then asks for 3x plus 2, and the value of x is always one of the choices. Underline what the last line actually asks for before you compute.
Sign errors when distributing a negative. This is the single most common arithmetic slip on the section and it shows up on questions you know how to do.
Ignoring units. Problem Solving and Data questions often switch between minutes and hours, or dollars and cents, in the setup. Write the units next to your numbers. The related geometry version is trusting a figure that is not drawn to scale. When a figure is labeled that way, the picture is there to mislead you about angle sizes and lengths.
When to guess
There is no penalty for a wrong answer, so every question gets an answer. On multiple choice, eliminating even one option makes a guess meaningfully better than random.
On grid-ins, a guess is a long shot, but type something anyway. A plausible number costs you nothing and occasionally lands, and a blank never does.