It's always supply and demand. How many seats are available on flights into those cities on those particular dates vs. how many people looking to buy those seats? Airlines have formulas for constantly adjusting their prices.
I watch as many options (days, dates, times, cities) as possible for a couple months - that gives me an idea of what a good price is. After that I'll jump on a great price if I see one. Otherwise, I'll book a good price maybe two months out.
I'd avoid Google alerts on flights. I notice they suspiciously alternatively raise and lower the price each alert. It seems more like a trick to get you to book quickly rather than good information on prices. Give it some time, don't be in a hurry unless you see something you know is a great deal.
I don't finalize any reservations or itinerary plans until I settle on the ticket because I won't know for sure which city or exactly what date I'm arriving.
I'm not a big reservations person anyway. I usually book lodging for only the fixed parts of my vacation. Fixed would be when I have a flight or other confirmed reservation that requires me to be in a specific place at a specific time.
Other than that, I travel outside of July/August and never end up homeless - even booking for the night the same afternoon. If you "need" to stay at a certain lodging, book ahead. For me anything clean, quiet and not expensive is fine. I've stayed in more awful places, and paid more, booking ahead than last minute.