the biggest problem you will face for using CPFP is when the wallet software that you are using doesn't have the feature to allow you to spend unconfirmed transactions. if it doesn't then you will have to use CPFP with unconventional ways such as creating the transaction yourself and signing through console,....
and usually if the wallet has that option it also has the CPFP option too in which case you should trust that it takes care of fee calculation and suggests the appropriate one (no need to use a website to guess the fees that are in most cases doing a very poor job).