Summary
There’s a variety of different cards, upgrades, and consumables to collect inBalatro, each with distinct effects and upsides and downsides, but none are as consistently reliable as the humble Celestial card. These are a common type of card you will quickly encounter in your run, but they can have a drastic effect on the game.
Each of the Celestial cards is represented by a different planet and affects a different poker hand in turn, and can be found individually, in booster packs, or through more circumstantial means. The more of these that you use, the better they become, slowly but surely upgrading your hands over the course of a run. If you make a point of getting these when they pop up in the store, even the lowest ranking hand can form the basis ofa formidable strategy.

8Earth
Full House: +2 Mult And +25 Chips
A Full House may be harder to reliably count on drawing when randomly picking cards, especially when in the early stages of a run before significantly modifying your deck, but it beats out both a Straight and a Flush right out of the box at even the most basic level.
Flushes and Straights may be the most tempting hands to default to due to their simplicity, but lesser or more rare hands can be just as effective when planned for accordingly. Hence, the Earth card.

7Mars
Four Of A Kind: +3 Mult And +30 Chips
If you can manage to draw it, a Four of a Kind is only beaten out, of all the default hands, by Straight Flush. Fittingly, then, the Mars card will bestow a bonus of +3 Mult and + 30 Chips, making a good hand even better.
It might require more luck than some of the more basic hands, but maximizing your chances for a Four of a Kind can be achieved fairly easily and fairly quickly with the help of other consumables such as the Strength or Death tarot cards.

6Neptune
Straight Flush: +3 Mult And +40 Chips
The Straight Flush is, in its basic form, the most valuable regularly achievable hand in the game. It is, accordingly then, more rare than the rest of the lesser hands.
As with Mars, the Neptune planet card will add a bonus of +3 Mult to all Straight Flushes played, along with a bonus of +40 Chips, ten more than for a Four of a Kind, meaning that after only one upgrade every Straight Flush played will be worth a baseline of +10 Mult before factoring in other variables such as Jokers and Mult cards.

5Saturn
Straight: +2 Mult And +30 Chips
Straights are a basic, strong hand, a good halfway point between the complexity and rarity of higher ranking hands and the commonality of lower ranking ones without sacrificing too much flexibility, especially with some of the more instantly powerful Jokers in the game altering your strategy.
With the Saturn card, you also get a significant boost in chips compared to some of the other planet cards, an important factor in creating larger payouts. With some forward-thinking, entire runs can be built around single hands, and Straights are an attractive option for this type of play.

4Jupiter
Flush: +2 Mult And +15 Chips
The omnipresent Flush perfectly straddles the middle ground between all the other hands in the game, to the point where it is perhaps all too common of a strategy to go for at the detriment to other possible builds.
It remains, though, a versatile and easy-to-build base for you to build your runs off in almost any scenario. Jupiter does not confer as many bonuses as other planet cards, but the ease of use Flush builds have more than makes up for this.

3Planet X
Five Of A Kind: +3 Mult And +35 Chips
The enigmatic Planet X is an aptly named card, upgrading a hand that is not normally available before altering your deck with Tarot or Booster packs, among other means. While a normal deck will contain four of every rank of each card in each of the four suits, adding in additional cards of the same rank will unlock the ability to play the rare Five of a Kind hand.
After this hand is played, Planet X can then be found or purchased either in the store or in packs of cards. Like its namesake, this is one of the more uncommon hands.

2Eris
Flush Five: +3 Mult And +40 Chips
What’s better than a Flush? The answer is simple: a Flush Five. A Flush Five is exactly what the name suggests, a Flush consisting of five cards, with the caveat that they all must be of the same rank as well.
This is something that can only be achieved by adding cards into your deck, thereby opening yourself up to encountering the Eris planet card. This can be surprisingly easy to build for if you go in with a plan to do so, as there are a wealth of options to alter your deck to include duplicate cards of similar suits.

1Ceres
Flush House: +3 Mult And +40 Chips
The Flush House is one of the hardest hands to build in the game, essentially being a Three of a Kind and a Pair, where every one of the cards played is of the same suit. If you can manage playing what is, more or less, three hands in one, you’ll only see further benefit by using the Ceres planet card and making a rare hand even rarer.
This is not something that is easily managed, requiring a good amount of planning to pull off, making it a very circumstantial strategy to aim for.