I would focus on the ETS GRE books:

For math, make sure you find the easiest way to do questions and identify / write down:

concepts tested
best method
anything you might apply to future questions like this one

For verbal, make sure you can explain precisely why the right answer is right or why any other tempting choice is not right.

Don't bother practicing verbal with non-ETS books, unless you're taking computer tests. Take a computer test every so often and especially take an analyze the Powerprep 2 tests (save one until the end of your prep).

Most people do hundreds of questions but few bother to fully understand the ones they do. So you'll learn a lot by analyzing ETS questions.

Don't feel too bad; I hear from a lot of people who work very hard on popular GRE prep (like Magoosh and Manhattan) but who are still struggling. You have plenty of room to improve.

Hi,

Happy to help you with this A2A.

Honestly,a 153 on Quant is slightly on the lower spectrum, but it is okay if you have been scoring a 158 in your mock tests. Your GRE scores can vary with a 5 point deviation, but ideally, your goal should be to score in the higher 160s.

Now to answer your question on how to improve your performance on GRE Quant.

Here is one Commandment that you need to follow while studying for the GRE - Anything that is not official is not reliable. So stick to official GRE practice books only! You can use the GRE OG 2nd edition and GRE Quantitative review to start with your prep.

These books cover the basics that are required for GRE Quant. Remember GRE tests your reasoning and basic math skills only. So don't worry too much if your math skills are still raw. The most important aspect when you solve a GRE question is to analyze which theory is being tested in the question. This way of strategizing your prep will help you understand the concepts better.

Don't quantify your prep time with the number of questions you practice. The strategy should focus on a review and analysis of the methods use to solve questions. This helps you build both your accuracy and timing on the quant section.

It is also good to do a small Q&A with yourself: For eg: When you get a question wrong on Quant, ask Why?
Was it because of
(a) Time Pressure
(b) lack of knowledge of the concept tested
(c) inability to comprehend the question
(d) careless mistakes.

You can also create a small error log with these 4 columns. Record the reasoning behind every wrong question on GRE Quant. This will help you understand your issue and you can focus on your prep accordingly.

Hope this helps.

All the best!