I did two runs in the prerelease league online, which is your normal sealed deck plus a foil rare. I did quite poorly, 3-2 and 2-3, but I managed to sell my opens for 29 tix, so that I came out even (counting boosters at 4 tix), and I like converting play points back into tix this way.

The reason I'm writing this is to warn you: don't play blue. My second pool had Niblis of Frost, Docent of Perfection, double Choking Restraints, Sleep Paralysis, Ironclad Slayer, Tamiyo's Journal, and Tamiyo herself. And it lost all the time to RG beaters. Every pool had removal for the flyers, and their creatures were simply better than mine. If I happened to draw my early white drops, they were blanked by Thermo-Alchemist. My wins came when I switched to RW, with Hanweir Garrison and Nahiri's Wrath. They say it's a bomb, but I never drew it.

In Sealed, Thalia is just a ridiculous bomb. I had her in my first pool, and every time she came down early, I won. And lost to an opposing one.

Lone Rider seems bad in Sealed. I had a few ways to flip it, and managed to do so a few times, and then it got removed. A lot of work for little payoff.

Look out for two untapped mana when attacking. Blessed Alliance is there to get your only threat off the board.

Kessig Prowler is a fine card. The can't be blocked by more than one creature clause almost killed me one game.

Everybody played red. With everything but blue. And it was good, sometimes great.

So fa, my take on this format is: play red. And then look at your pool to see if you need to add another color.

Red / blue is quite strong in draft as well.