I am going to present my PMP exam next month, could someone give me some recommendations or study techniques to approve?

If your exam is in a month you must have studied and performed several simulators.

The best test is to perform several simulators to detect weaknesses in order to reinforce them and ensure that you can pass the exam

There are many similar discussions here started by people preparing for their exam, you may want to search for them.

Simulation exam is a must.
Prepare what you need to write, they supply pen and paper. Example formulas CPI EVM....

1. PMBOK 5 Guide contains a chart of ‘Project Management Process Group and Knowledge Area Mapping’. Keep this chart in front of you while studying for the exam.
2. Read PMBOK 5 at least twice. Entire exam content would be based on this book.
3. If possible, try to subscribe chapter wise tests on pmstudy.com . Those tests are helpful and will help you to clear all doubts about concepts.
Read more on: http://www.pmpchapterquestions.com/pmp-tips-and-tricks/

Strategy to follow while answering situation based questions, you should:

Step 1 – Carefully read the full question and try to focus on the real PROBLEM/PROCESS/SCENARIO being tested. Ignore all the extraneous information and description.

Step 2 – Read all the answer choices and try to eliminate choices that are clearly irrelevant and out of context for the question.

Step 3 – Read the remaining choices carefully and decide which one best answers the question. This is where you own experience as a project manager and the ability to apply PMBOK concepts in real scenarios comes handy.
good luck

Not just the preparation is important, but also being a smart test taker. Good Luck.