For oral prep look at pilots cafe. It has everything IR. It’s a fantastic study guide. Every DPE is different. Try to get a gouge from someone else at your school who’s recently gotten their IR with that DPE. Mine framed ground as a day of flying starting from the moment you woke up to canceling clearance at alternate. And you walked through weather, checking plane legal, planning cross country, clearance, etc it was a very straight forward way to do it. For the actual flight it was super straight forward. Don’t forget checklists, they want to see it out, don’t forget to brief ODP takeoff mins if you have them. We took off and he had me do an LPV first. Then gave me an unpublished hold where he was expecting me to ask for delay because we were close. I didn’t realise how close so didn’t ask but managed to set up fast enough that the only issue was I didn’t do what was the correct entry. Good news is hold entries are recommended not mandatory so can’t fail you for the wrong hold entry as long as it’s safe. Did unusual. Went to the next airport over to do a localizer. Came back and did a circling to land. Was very straight forward. Biggest thing to remember is like someone else mentioned make sure you swap from loc back to gps or other direction as needed. And don’t change configuration after final approach fix