This you probably already know, but if you don't, it helps. Basic tree ID has two groups, and I'm just talking native trees up here in the Midwest, which is quite similar to PA.
Group 1: Opposite branching -- has to be MAD -- maple, ash or dogwood (included in the maple family are things like box elder).
Group 2: Alternate branching --everything else. So if my eyes had picked up on opposite branching in that photo, I'd have thought, "Ash or maple? Probably ash. Or some ornamental I don't know (though the bark and leaves don't look like ash to me).
This makes maple, ash and dogwood real easy. Maple is very distinct from ash -- leaves and bark. Dogwood is the only small native tree in my region with opposite branching. Right away you have three genuses you can nail.
Once you know your region, other regions can be pretty easy for the genus. Maples tend to look like maples. The species will be different, so here in the Midwest sugar maple is common (red too), and in the Northwest big-leaf maple is going to be common. But your first time in Washington you'll automatically know it's a maple. Spruces are spruces, but have different species. Pines are maybe toughest for the species, but you can nail the genus all the time. Even little mugo pine, from Japan, is obviously a pine.
Arboretums also help -- labels. Though a lot of the trees will be ornamentals. If you're ever up at Cornell University, maybe their forests next to campus have some kind of labeled trail.