What may also help you is just searching the function or variable name in every single source file (I use Notepad++, press ctrl + h and hit the search in files tab) in order to see where the function or variable is used or where it points to.
If you don't have any pointer as to which function or variable to lookup, you might just want to search for the native callbacks. For example, if you know a bug occurs when a player enters a car, search OnPlayerEnterVehicle or OnPlayerStateChange in the source, and then quickly skim through the code under the callback in order to find the function that may be fucking something up.
That'll get you through a maze of code before you get where you want to be but I find that to be the best way to get familiar with the code structure. After a while you'll be able to skip these steps and you'll have an idea of where to look for something.
If you don't have any pointer as to which function or variable to lookup, you might just want to search for the native callbacks. For example, if you know a bug occurs when a player enters a car, search OnPlayerEnterVehicle or OnPlayerStateChange in the source, and then quickly skim through the code under the callback in order to find the function that may be fucking something up.
That'll get you through a maze of code before you get where you want to be but I find that to be the best way to get familiar with the code structure. After a while you'll be able to skip these steps and you'll have an idea of where to look for something.