I'm not necessarily looking for theory of any particular subject but rather a more general approach to how theoretical physics is actually done in practice: -What problem-solving strategies do physicists use? (Most important part for my interests, I'm getting back into math competitions and I want to round out my problem-solving skills with some real-world applications). I've read and worked through plenty of math problem-solving and proof-writing books, but I'm looking for real-world applications. -How does a physicist derive a theory from experimental data? -When is a theory considered fully derived as opposed to just conjectured, and how does a theoretical physicist go from conjecture to theory? I'm looking for a book or resource that answers these questions and gives an introduction to the methods that theoretical physicists use in their work. I'm not interested in derivations or proofs of results but rather how theoretical physicists figure out how to derive and prove their results in the first place.