Davo gave you great advice. June fishing can be exceptional, but a lot of the easier less selective stocked fish may have been cleaned out, or have become more acclimated to natural food sources. There are also some major hatches that tend to be harder to imitate with some of the standards that you might already have in your fly box because of their large size (Eastern Green Drakes and Stoneflies), light colored bodies (Sulphurs and Light Cahills).
A local fly shop (as opposed to a big box store) can give you advice on flies that might be working now--- most shops will have "hatch charts" for their local streams, and will be wired into the up to minute conditions. Hatch charts are available on line too like this one for NE PA:
Not all hatches will occur on all streams--- or on all sections of streams, but the hatch chart will give you a good idea of what to expect, when the best time of day tends to be to be on the stream to catch the hatch, and what the best "stages" of the life cycle tend to be the most important. Major hatches in June in PA are Eastern Green Drakes, Sulphers, Light Cahills, various Caddis, and Yellow Stoneflies. If you're going to be fishing in June, it would be a good idea to pick up a few patterns to add to your basic fly box of standards (like Woolly Buggers and Parachute Adams that are good go to flies but may not work as well during these hatches). To actually match the hatch, although a bit more expensive than discount flies, it's always a good idea to get locally tied patterns from a shop to match local specific hatches- as opposed to flies tied in Kenya or Thailand since there can be a lot of local variation in size and color of the naturals. A hatch chart like this is good to get a sense of what might be going on, but adding info from a local shop on what hatches are actually happening, specific flies to match them, and some advice on where to try-- specific sections could really help you get into them.
A site like Troutnut.com Fly Fishing for Trout
has tons of info on different hatches, and you can look up different mayflies, caddis, and stoneflies by their common (or better, their scientific name since common names are often used for more than one actual critter) to get detailed info on where to look for them in the stream ( fast water, or slow water stretches), detailed pics of different life stages so you can recognize them on stream, and fishing tips for that particular hatch. In addition to helping you learn a lot, it will also probably make your time on the water more enjoyable when you do connect if you put some planning into it and it actually works... And if nothing else, it will give you a profound sense of awe for the whole circle of life thing and make your time on the water more enjoyable fish or no fish.
Finally, I always suggest folks hook up with a local fly fishing group like a TU Chapter Council/Chapter Search | Trout Unlimited - Conserving coldwater fisheries
or club affiliated with the Federation of Fly Fishers:
Locate a Club
Joining a group will really shorten your learning curve and most are very welcoming to new folks. They typically have fly casting clinics, tying classes, group trips as well as informative meetings, and you're sure to get a ton of info that would take years to learn on your own by trial and error.
Good luck and keep at it. The more time you spend on the water the better, and if you can add some good intel before hand from local knowledge, you'll increase your chances exponentially.
A local shop can also give you more specific information on where to fish--- if you're fishing for trout but mostly catching sunfish, you may be fishing in the wrong place.