Baltimore County covers a broad mix of communities with different relationships to the city. Towson is the seat of county government, while places such as Catonsville, Owings Mills, Cockeysville and Dundalk have distinct local centers. A county overview is the beginning of a search; the useful detail is the particular community and its connections.
The northwest side has a clear transit reference point in Metro SubwayLink. The line starts at Owings Mills and runs into Baltimore City toward Johns Hopkins. Check the actual stations and onward connections when considering a journey: being in the county does not by itself put a destination on the same transit corridor.
For an outdoor destination north of the city, Oregon Ridge Park in Cockeysville has woodland trails, a nature center and a lodge, with access from Beaver Dam Road. Use the entrance that corresponds to the part of the park you plan to visit.
The same level of detail helps with everyday decisions. Compare where you would shop, which local services you would use and the route home, then explore the streets and public places around those stops.