All these tips are excellent. I'll add a few of my own.
Listen to what other collectors or dealers talk about, IOW eavesdrop. You can learn alot about the latest collectible coins, what's hot and what's not, whose prices are lowest, etc.
One thing I've learned through the years, the really good stuff is kept under the table.
On average, the prices are higher at shows. Doesn't matter if it's a coin show or a car show - they mark up their prices for the show. There are exceptions to that general rule, so keep your eyes and ears open.
This is gonna sound strange, but here goes anyhow. When I go to the coin shows, I look for old books. When I go to the book shows, I look for old knives. When I go to the knife shows, I look for old coins. IOW, I avoid the obvious and look for the odd because you can usually get better prices on stuff when it doesn't fit in with the main focus of the dealers. It's the rule of contrariness. Try it, it is fun and rewarding. Just don't be obvious about it, act casual.
Take a small pocket notebook and jot down stuff so you will remember what you heard, learned, saw, bought, prices, etc. It is much easier to write it down at the time than to try to remember everything after you get home.
The best thing to keep in mind: learn to walk away if the price is out of your range.