This topic is quite hard and honestly, you have a better chance of reaching out to the plugin’s support team so you can ask what filter to use in order to achieve x. Since you are here they don’t have support or their reply times are horrendous and or are of no help.

So here’s what I do in order to find the filter to mess around with

1- Read the documentation, seriously just go through the plugin’s website and read the documentation. If they are large enough or have great documentation chances are they have developer-level documentation that states what filter is available and what it does.

2- Sometimes the plugin is so well known you can just google it, Just go with [plugin name, available filters] and it should spit out some person’s blog or website. I do this all the time and save lots of my time. I usually go to this website for my Woocommerce needs and or questions WooCommerce¬†Single Product Page Hooks:¬†Visual Guide (businessbloomer.com).

3- This is a last-ditch effort, go through the plugin files and read their code. This is the worst since you literally have to go through the plugin’s code in order to find what filter is available. If the plugin developer follows the programming standard for naming functions then it should be quite straightforward. An example would be function calculate_tax, from the name we know it calculates tax

Some tips

When you read through the code, you can just hit the ctrl + f and find the filter or actions. Once found scroll up or down and see if it matches your requirements, doing this helps me find the correct code to work with and it should help you.

Stackoverflow is your best friend, no seriously that site is the bible for programmers. From newbie questions to advanced questions, chances are your question is there. Well, this mostly applies to programming questions, so if you don’t have the basics done you might have a hard time understanding the questions or answers.