The Port of Baltimore might just be the easiest port on the East Coast to take a cruise from. It is right off of Interstate 695 on the Baltimore Beltway. The cruise ships are easily spotted once the offramp has been negotiated and the beltway overhead is gotten past. The entrance to the cruise terminal is on the right side of the road and accessed by driving through a chain link fence gate.
When you drive into the port area a ground guide will direct you to the baggage drop off area. This area has baggage trolleys that porters will load your baggage into. It might be a good idea to have your baggage tags attached to your suitcases before leaving for the port to make this part of checking in easier and faster. It is typical and customary to tip the porters $1.00 per bag.
After dropping off your bags a ground guide will direct you to the cruise parking area. This is immediately adjacent to the cruise terminal.
My experience with checking in at the Baltimore Cruise Terminal is that if you arrive early you are in for a wait. When arriving before 11:00 you are going to be directed to a waiting area that has the traditional (uncomfortable) plastic chairs until boarding begins. Arriving after 12:00 I have typically been able to proceed directly from the check in line to the gangway.
Fort McHenery (think Star Spangled Banner) is very close to the Cruise Terminal. If you are real early you may want to consider checking your bags and visiting the fort. When the ship leaves the port you will have a very good view of the fort from the aft of the ship. This is a nice historical addition to sailing out of Baltimore that you should take advantage of.
Royal Caribbean and Carnival sail regularly out of Baltimore and Norwegian Cruise Lines occasionally sails from here. If you live in the Mid-Atlantic area Baltimore is a convenient plast to cruise from.