If you're going to tackle Hard, you're going to need to be fast. But speed is not how you win - you'll need to pay particular attention to power-up management
. That doesn't mean getting as many power-ups as possible or creating the highest chain possible. That means managing your power-ups efficiently and effectively. You also want to make sure each third match is in a place you can get to. A Frost Ray is no good if you can't reach it.
Put a lot of focus at the start of the days into setting up chains. Make loner colors paired and ready for a quick strike. Once you get rolling, the power-ups will do most of the work. You can change your load-out by pressing Menu and selecting Inventory from the map. I always use the same load-out. Details below. Spark Blast (tier 3)
The worst power-up. If you get one, just shoot it at anything that looks color-scattered. The lower tiers are just less sparks, so you'll have to make this work. Note that Spark Blast will not hit anything in tunnels or in the hole. Marching Light (tier 3)
I stick with Marching Light because of its ability to rescue you from a dire situation. If you have orbs in the hole, it will take them out. The biggest issue is that you may have been setting up the front of that orb snake for combos, so be careful about when you grab this. Double Wild Orb (tier 3)
Better than it sounds. It will instantly give you two matches, assuming you didn't hit a pusher or an end of an orb snake. Once you have two, that only leaves one needed for the next power-up. This is one that you can save until you need it by pressing B to continually swap to the back-burner. Color Blast (tier 2)
Tier 3's Color Wipe is just too inconsistent. The way snakes tend to wrap around each other, combined with Color Blast's AOE, makes it great for knocking out big snakes at once. If the match is large enough, you'll also get a neat effect where a few of the next snake's orbs will be instantly destroyed. Note that color blast DOES work through tunnels, assuming the orb you hit is above ground. Enchanted Fireflies (tier 2)
My favorite. Tier 3's Wrath of Moon is sneaky, in that it seems to be one of the best power-ups. It's good, but not as good as this. The fireflies allow for more power-ups quickly. They also hang around until they are needed. Brilliant grab - you'll learn to love these. Frost Ray (tier 3)
The mighty Frost Ray. Devastating to large amounts of orbs, can shoot through holes and tunnels, and destroys anything in its path, no matter how many are in its way. Great for taking out wrapping snakes or days with multiple snakes. Always try to maximize what you're getting out of this. This is another that you can keep on the back-burner by swapping it out with B until you really need it. Great for emergencies, too.
Again, you want to focus on managing these efficiently. That's your primary focus. If you've also got blinding speed, even better. I don't feel like I'm particularly fast, but I was able to make it through Hard. I'm currently working on Nightmare.