Yarium posted an excellent guide to sealed for new players. As additional reading, I propose to show you a bit of my deckbuiding process from my last sealed league pool. This will probably be a long and time-consuming post, so I will post it in parts, hopefully with match progress reports.

Step one is, of course, a first look at the pool:



This can be quite daunting, more so for a player new to sealed play. White and black are the longest colors, and there are two great gold uncommons.

How do you start building a sealed pool? The first step in the guide is, find your best cards. Let's try it.

I usually start with the rares and gold uncommons:



This looks fine. In fact, I was quite excited to see it, as I've been wanting to try a UW flying Zombies deck in Sealed for some time. Rating these cards, Approach of the Second Sun, and Commit // Memory are more or less unplayable, Soul-Scar Mage is only playable in a full-on aggro deck, Prowling Serpopard is fine but nothing more, Ahn-Crop Champion requires an exert deck to be anything more than an on-curve beater, Curator of Mysteries is a great card that pulls me strongly into blue, Aven Wing Guide is excellent in a UW deck and a bomb if you can produce tokens, and Vizier of Many Faces is, quite simply, a bomb rare. So, first thing I will try is a UW skies/tokens deck.

The next thing on the agenda is removal:



Here we have all the cards that can function as removal, however situational. Top half is removal, bottom half are tricks, ordered into columns by quality, ranging from Cast Out which is one of the best removal cards in the set and a card I would strongly consider splashing white for, to Blazing Volley, which in Sealed is at best a sideboard card.

It should be obvious by now that white is our best color, and blue is a strong contender for the second color. We should also keep in mind that we have two first-class red removal spells.

And now, the hard part. For this, I like to start by separating out the good playables that I will always play if playing that color, and ordering them in piles by color:



This parallels the 'junk 'pile' step in Yarium's guide. However, there are important differences. For one thing, it's way more subjective. I'm sure some of you are shaking your heads over my choices. It's also more productive.

Green looks to be our worst color, with only three good cards. We will not be playing that.
Next up is red with four cards; these are all very high quality, but unfortunately, there's not enough of them, and the rest of red is mostly just chaff.
Blue is also short, but it has a bomb rare and some very solid cards. Of note, we will be playing white, so for this step we can count Aven Wing Guide as a blue card, which strenghtens the color considerably.
Black is very nice, with a lot of solid cards, and some cards that work very well in the right deck that I left in the top pile. We should consider this one.
White is definitely a color we will play. It's excellent. Depending on our build, there's a lot of additional material in the top pile. And Oketra's Monument is a very good card that can reach bomb status in a white go-wide build, and has great synergy with the Wing Guide.

So, our path forward should now be clear: let's put together a UW flying Zombies deck and a BW value deck.

Oh, wife just came home. We'll have to continue this tomorrow. As always, all comments are welcome.

Sounds good so far! White and Black are definitely the best overall, but blue's got your best cards in it (Curator of Mysteries is probably the best card in your pool). There's a definite W/B Zombie midrange deck here, and I think that'd be the strongest one to go into. To top it off, I'd put in the cycling rewards with Ruthless Sniper and Horror of the Broken Lands, along with Supply Caravan and Oketra's Monument.

That'd be the deck I'd stack everything up against. Because I'm a glutton for punishment though, I'd also try to see what a Black/White/Blue cycling for Approach of the Second Sun control deck would look like.

This is a tough one. WB looks more consistent with like 9 zombies but your two bombs are blue. I think Vizier is certainly better than Curator of Mysteries.
Normally in sealed I think you just pick the best Vizier of Many Faces deck, but you also have In Oketra's Name and Time to Reflect

Zenith Seeker is marginal at best though, I would try to not play it.

This pool could use a couple of Evolving Wilds.

My deck is the 15 cards below the fold in W and B, Plus Oketra's Monument +
2 x Festering Mummy
2 x Blighted Bat
1 x In Oketra's Name
1 x Time to Reflect
1 x Horror of the Broken Lands

Not sure about 17th land vs. Cartouche of Solidarity, and maybe I want Supply Caravan over Grim Strider.
Oh I think I play the Cradle as 23rd card.

Thank you for the comments. I somehow managed to overlook In Oketra's Name.

Time to build some decks. BW Zombie midrange value:



The main strangths of this deck are:

Its mana base - 8/8 Plains/Swamps, making for great consistency, with a few cyclers added in we can use to draw out of mana troubles.
The creature curve - Binding Mummy into Cursed Bat into Bone Picker can win games.
A bomb uncommon in Lord of the Accursed. That card is simply ridiculous in a Zombie deck.
All (OK, if you insist, most) of its cards are fine playables. Time to Reflect is excellent in this deck.
The sheer amount of playables, there are some tough choices in there. Like not going for the cycle value, or Unburden over Djeru's Resolve, or Horror over Caravan.
Some nice sideboard cards. I can see winning a ground stall using Embalmer's Tools, for example. Not very likely, but a thing I will keep in mind for some matchups.

And the weaknesses? To use Yarium's terminology, it has a low ceiling. Yes, a high floor too, but if a deck can stop our main plan, we just lose. No big turnarounds hidden in these 40. And it's not particularly fast, with very few sources of card advantage. A mindless grind. It is also missing embalm creatures in general and Unwavering Initiate in particular.

Well, enough with foreshadowing, let's look at UW:



This deck has a very simple plan: attack for three in the air on turn three, stall the ground with Labyrinth Guardian, draw cards, remove some creatures, win with bombs. It is not the easiest deck to play, and I would definitely suggest the BW deck to a beginner. But I simply can't resist playing this. Blue Cartouche returning the red Trial. Untap effects eating opponent's attackers. Wing Guide + Monument creating an army of 1/1 vigilant fliers. Vizier! And to top it all, if the creature attack plan does not work, we have the rare combo, Approach of the Second Sun + Commit // Memory. And the option to switch the splash to black, for Zombie lord and Wander in Death. I prefer the red removal option, but against some decks, the Trial is not very good, and I could see switching.

Call me crazy, but I'm playing this, and with a bit of luck and good draws, I won my first two matches. I plan to report further when I crack the next booster.

3-0. Trial of Zeal dealt the last point of damage, just before my UB control opponent was able to stabilize.

And now for the best moment, the booster:



Eh. A single UW playable, tow nice black cards, and two great red cards and green cards. Meaning, we have to start from scratch, looking at all the colors again. Red has a lot of high-impact cards!