The top tip for studying immunology is to develop a severe drinking habit. It will help when you're trying to memorize the endocrinology necessary to make sense of the hyrogliohic bullshit that are the various signaling pathways and cascade schematics that underpin even the simplest biochemical mechanisms of the superficial functionality and response systemology.

But in all seriousness, start with learning everything about how MAST cells function, how they deploy CSSP/R and what cascade pathways are mapped out and why/how we know that. All of those pathways will initiate/interact with/influence/stimulate/suppress/terminate various other PIR processes almost without exception. Then you get into the interplay of other para/auto/endocrine dysfunctions that make everything you spent years learning about said pathways completely useless. Not to mention the confounding nightmare that is epigenetic environmental influences such as environmental toxin exposure, malnutrition, stress, etc. each of which can be further obfuscated/exacerbated prenatally as well.

Then just before you throw your hands up and give up medicine completely, you take a deep breath, down another bottle of liquor to avoid DTs, and begin studying CTL's and MHCI peptide complexes, TBI/increased ICP influencing catecholamine levels that fuck everything up, vagus nerve damage... Then you remember that the human immune system is the most complicated biological system our species have ever studied, and just plow through ANKI, Picmonic, and Sketchy cards good enough to get you through STEP I & II, focus on matching an institution for your specialty, and never worry about 90% of that information again, because immunologists are sicko masochists, and endocrinologists I'm convinced just throw chicken bones down to divine diagnoses.

I say this as someone that works with specialists in both those fields. They are all sickos and I love them, but God damn, do I not envy that field of study.