The freezer is your best friend here! If you can catch insects just throw them in a ziplock bag and toss em in the freezer. Once they’ve been in there for 48-72 hours you can pull them out and let them thaw on the counter for about 5-10 minutes? Depending on the size.

From there it’s kind of trial and error to get the pins in straight without knocking off any legs or antennae but usually when you’ve frozen the insects they stay pliable and you don’t need to relax them. All you need is some styrofoam or something similar and the pins. If you want to spread butterfly wings you can get relatively inexpensive spreaders like this one which is the exact one I use and it works great!

The best advice I have is to try to be able to identify your insect to the order level. That will help with knowing where to pin the insects! It’ll always be in the thorax (middle body). Or simply google search and match based on what it looks like most. This site is a great resource to know how to preserve specific insects.

I suggest using size 3 pins like these for most things. For really small stuff they use things called points (small triangle pieces of paper that you glue the right side of the insect to). But if it’s just for your own personal collection of larger stuff you like no need to worry about it!

There’s stuff that can be permanently kept in plastic or glass vials of ethanol (usually 95%).

Hope this helps!!