There are many ways to prepare for Modules 3 & 4 on the ProAdvisor exam. I'd suggest taking the exam right after you have studied the section for that module.
You might find the tips listed below interesting and helpful:
You have to pass all the modules with a score of above 80%.
You only have three chances for each module.
Modules can be taken in any order.
All the modules are independent of each other, but if you fail any one module three times, that means you fail the entire test.
If you do not pass the test in three tries (even just one module), you must wait 60 days to attempt the exam again and will have to pass ALL modules (it doesn’t matter if you passed 9 modules on the first try and only failed one section 3 times).
The following resources are good references. You can sign up for the training where you can have access to the tutorials and webinars to get the most out of QuickBooks: