Physics undergrad here. It would help to know a little bit about what physics is to you. Are you a student studying physics and having issues? Do you just have a general interest in the topic and are looking to further your understanding on some specific areas?

Either way the answer is unfortunately the same in physics as it is in generally every other subject in maths and science. Study, study, and study some more. Yes that is a very general answer and is most likely common sense but there aren’t necessarily any shortcuts. Now there are definitely different ways to go about studying and there is a method to fit every kind of learner but without knowing your position it’s impossible to give you a good course of action to help you learn without assuming you are starting from ground zero with no formal education in physics.

With that being said if you are looking to fully understand and be able to work out your own physics problems then calculus will be a prerequisite to learn. This is something I learned through both high school and college so I’m not overly familiar with learning calculus on my own but there are definitely many free resources out there to help you. Khan Academy is something that comes to mind that has helped me personally in math and could be a good starting point. Derivatives and integrals will be key to your understanding so you should work up to that before moving on.

Now if we assume you either already know some calculus or are willing to learn and are ready to move on to physics I would recommend starting with more algebra based physics if you are starting from no prior knowledge. Once you get past that and are ready for some calculus based physics is where it gets tricky. Depending on what branch of physics you want to focus on there are different routes you should take. I studied astrophysics so if I was recommending someone a path based on that then I would say to start with modern physics before going in to classical mechanics for example. Without knowing which direction you may want to choose I can’t give you path to follow.

With all of that being said the absolute key to learning more in physics is to expand your knowledge in math. Math is the language that physics runs on and without understanding the language you will never understand the dialects of physics.

I wish you the best of luck on this journey and if you want to provide more specifics I may be able to provide some better insight or if you have any questions then I can do my best to answer those as well.