Hi Joe,
I think because Loch Raven is so big it can be overwhelming trying to figure out where to go. The most reasonable approach is to find the access points where you can park.
Drive up Dulaney Valley road until you get to the bridge crossing the Reservoir and park to the left, I think you can still park there. Then you could fish off the bridge like in OC, or walk along the shoreline & find a spot. If you go further on Dulaney Valley rd, about 1/2 mile up on the right is a place where you can rent a Jon boat. It has a launch point and you can go out from there. The rules are pretty strict about bringing your own boat. If you don't have a permit already you wont get one now. They sell out within minutes. https://www.baltimorecountymd.gov/Agencies/recreation/countyparks/fishingcenter/
Go up 83 to Warren road and go down that road (several miles) until you get to an old metal bridge. Go across & there is parking on the left and right. I have fished there on both sides. On the right there is a big cliff you can perch on top of & on the left there is usually a shoreline or sandbar depending on the water level. There is another access point if you continue down Dulaney Valley another mile or so. There is a part where DV rd makes a 90 degree turn, where Pierces Plantation restaurant used to be. If you go straight there it's Loch Raven Drive, you can access the shoreline there for several miles. Sometimes the road is closed and only allows access to the first mile or so. If it's not closed you can go all the way to the dam. Otherwise the dam has to be accessed from Cromwell Bridge rd. or Providence rd.
There are probably other access points but those are the ones I have used. I'd love to hear if you have any success. It's been a while since I have fished those so I apologize in advance if things have changed.