There might be also a practical hint for starters: If you get light trap results from a Pennsylvanian light trap, you sometimes have hundreds of insects during one night. So the first thing is to compare them and build lines on a table for the individuals of each species you find. (there are freshly hatched and those that might have lived for a while, loosing wing scales etc.) Give them numbers and keep the most well conserved in Petri dishes, with their number. Establish a list with numbers attributed to the specimens, and count how many you find each week of the same. (Later on, when you got the experience, and the first names, change the numbers for names). You might end up with many dozens of types. Then take picture books in any language available (there are in fact many excellent books in German, or English, but also in French etc.) and compare pictures with your insects, read about the seasonal appearance and host plants, find out weather in your surroundings it is possible to find those species. Keep in mind the latin names and go to internet with those latin names to find more pictures and identification literature. Confirm with specialists your findings. You can send difficult to identify species to the British Museum of Natural History, they have a payed (!) identification service. There might be closer taxonomists though. Keep in mind that scientific names change constantly (?) as new species are discovered ... it is a living and very dynamic science. Good luck!