I was just wondering if anyone has advice on what parts/things to pay special attention to during the R22 preflight
Not so much specific things to look for but the way you do it. I was taught by an old and previously bold instructor pilot to do a meticulous preflight using a custom paper checklist which incorporates RFM items, items unique to my helicopter, and "gotchas" learned over time but not in the RFM checklist. Each item is checked off as done and the checklist is signed by the pilot or mechanic doing the inspection, and then filed for future reference. Some (many?) will scream "overkill" but I have found that this instills a discipline and a pace to the preflight that helps to avoid overlooking important items. It is impotrtant not to be rushed when doing the preflight, so best done in a warm hangar out of the wind, rain and cold if possible. I use a similar approach to fueling, with each addition of fuel documented, signed, and filed. Again, encourages discipline and a safety mindset. And if you adopt this approach, it is important not to short circuit it even once in the interest of speed (except possibly in an emergency). Over many decades of flying I have observed that many pilot are always in a big hurry (me too at one time) and this will eventually bite.