Before becoming a mason I worked for a landscaper in bucks county not far from you who only put in new lawns
Spring is a good time but once it drys a bit. You said it is patchy, if your yard isnt real big your best bet would be a rototiller,if you dont have one you can rentone. Rake it out as level as possible and remove large rocks if any. Most home stores sell a contractors mix ,But Im sure out there in berks you can find a feed mill that has it. Make sure it contains some sort of Rye grass for a quick growth ( 7 days or so ) and a good red creeping fescue. use a spreader and spread it as even as possible . It does help if you can rake it into the dirt, we had special rakes but a bambo grass rake will do. Also use a 10-10-10- slow release fertlizer. I recomend spreading a thin layer of straw on top when your done and water it regulalry. The straw will eventualy mulch in so dont try to pull it up if you can resist it .
I hope this helps
