On a 5x8 index card, I put important phone #s (ER, lab, blood bank, radiology, dietary, faxes, and the different extensions in the unit). Doc's pagers. Critical lab values per facility lab (some hospitals say you have to notify the MD if X>Y within 30 minutes, 1 hour, etc., know your facility's policies). What tests make a person NPO, NPO past midnight, early light tray, etc. Creatinine clearance needed for specific tests. I work nights, so I tried to put the data you needed when there was nobody around to ask. "laminated" it with wide clear tape, kept writing things I needed to add on the back.
Over time, as the card got full, I went to a small 3x5 card spiral bound card pack, which had 5 different colors of 3x5 cards. I made Docs one color (page with phones/pagers, page with what which doc wants in the room for specific bedside procedures, things like their glove sizes, picky things they want for specific situations). Another color was for procedures -- what you had to be NPO for, specific dietary or medical requirements (hold that metformin!) and numbers to all the different areas (endoscopy, same day surg, radiology, etc.). What we did the consents/check sheets for, what was done by the specific area (cath lab wanted us to do it, endoscopy wanted to do their own). For the 3rd color, I put all the cardiac "stuff" -- 1st degree is PR interval > .20, what it can be caused by (hypokalemia, inferior MI, myocarditis, etc.), and I taped a sample of a telemetry strip (no name, of course). Specific stuff for specific meds -- Cardizem can go IV, hydralazine will decrease BP without increasing HR, just whatever.
The trick is, start small, and add as you go; keeps you from getting a lot of data you don't actually use cluttering things up. By the time I left my first hospital, they took my little 3x5 card notebook and were making copies of it as a new hire handout.