I lived right beside Pymatuning for years and fished it a bunch. The area I fished the most was on the west side and lower end. The dam area to Westinghouse bay mostly. I would throw jigs (yellow, white, light green, black/silver) up until dusk wading with hip boots then switch to rapalas (black/silver) to a little after dark in the early spring and late fall. Fishing with chubs at this time works great too. Don't forget about drifting small chubs casting from shore in the river just below the dam. Pymatuning has the best shore access of any lake I know of.
I always had a small boat with an electric motor on the transom to use as well but found that fishing from shore wading produced just as well and was much less hassle. Lots of nice walleye to catch both spring and fall. Best times are about a couple hours before dark to an hour or so after but you can catch them at any time.
Fishing the stumps on the upper end for crappie is hot in the early spring and clear through to the summer. You need a boat to get out there though. A canoe actually works better in the summer because of the thick weed bed. The Linesville launch is where I used to go.
There isn't as much shoreline access up that way. There is a fishing pier now at the PA causeway livery but I have never fished from it. I also used to go under the causeway on the PA side and fish the boat tunnel with a slip bobber and did pretty well. You can fish the sides of the causeway from shore as well.
The Linesville spillway is a favorite for a lot of people but there is usually a bunch of people there if the fishing is good. Sometimes you can get a spot and sometimes not. I did well there when I fished it but seldom went because of all the people.