1. On finding M13… when starting out, It's all too easy for many to mistake other collections of stars for the Keystone. I remember, when first trying to track down M13, looking and not finding it many times — it turned out to be because I didn’t recognize or mis-recognized what the Keystone was!
So, a good planisphere or star chart — and lots of naked-eye practice at picking out the constellations is crucial. The finder helps get in the ballpark (under good transparent dark skies, you can pick it out in finder). Then, once with the telescope, a low power wide field of view eyepiece is essential for sweeping it up. Ramp up the power after you find it!
Also, in smaller scopes, M13 is not as fetching or impressive as other globulars are, such as M22, M5, and M3. Or, even M4 with its string of stars.
2. A big shoutout for Turn Left at Orion! It revolutionized my star hopping and astronomy pursuits. It's a gem. The combination of constellation, finder, and telescope views is well designed, a joy to use, and makes finding things a piece of cake. The sprinkling of good scientific information makes the entire journey even more enjoyable and helps you appreciate what you're seeing. Highly recommended book!