How do you let the players in your campaign be cool?
Ideas are always given a chance of success. If it's particularly inspired, it may get an automatic success. I push players to think outside their powers, outside their optimized character sheet. A wyvern is flying out of reach? Attempt to use that smaller tree as a catapault, launching you up to its height (that's an athletics check allowed as part of the move. If successful, he's launched up to strike or attempt a grab to keep from falling)
Do you use lots of minions?
YES!!! Minions represent the henchman, the guard and the bandit. They are many, but they go down quickly. The more powerful characters are recognized. They speak, they shout orders, they use minion's aid. The heroes know when they're encountering minions or more dangerous foes.
Give them bonuses when they use the environment appropriately?
Up to and equaling absolute success. If someone comes up with a clever idea based on some terrain, or they've got the high-ground, they'll notice the shift. In some areas, primal characters gain bonuses for being near ancient trees...
Design little sidebars to showcase their strengths?
I'm not sure I follow, exactly...
Other things I do - the more my group "investigates" before they attack, the more they learn. If they run willy-nilly into a fight, they'll only have what they see on the map. If the warden checked out the land, however, he'd notice that there's a strong primal connection near that pool, and any slide effect is increased by +1...or the rogue may notice that most of the trees above could be easily traversed stealthily, allowing sneak attacks from above...
I also tend to ensure combats are rarely purely "Attrition". Sure, the players can just kill everything, but that doesn't gain them the same benefit as stealing the leader's sending stone that was hidden during the ambush. Alternatively, just stealing the sending stone would allow them to bypass the enemy and damage their communications...
In the same vein, harder encounters almost ALWAYS reap an instant reward. For instance, in a recent encounter with undead "that appeared to be random" the party defeated the creatures and discovered it was a mystical trap, housing the eye of vecna from would-be theft. Of course, the players now have the eye and can choose what to do with it...