Master Duel has a fairly generous system, as you are able to dismantle cards you don't need and generate ones that you do! However, it can be quite troublesome if you're unfamiliar and inexperienced. Today I'll be lending a hand and giving players a general guide on what to do. Let's dive in!

Interface

Here's what you can see on the left-most side of the screen in the deck builder. Cards can normally be dismantled for 1/3rd of their value, giving you 10 CP of the card's rarity. For example, dismantling Majesty Maiden here gives 10 R CP. In some cases, dismantling can give more. Glossy cards provide +15, while Royal Flushes can be dismantled for their full value. Generating a card will require 30 of a particular rarity's CP.

How do I get started?

"That's great and all, but I don't have any cards to dismantle with. Where do I start?" Not to worry, aspiring Duelist. You can spend your gems to pull cards from packs!
For new/returning players, I recommend this route: Get all the bundle deals, which nets you a free Solemn Judgment, Ash Blossom, and Lightning Storm! Those three cards will serve you well during your stay and can be used in several different strategies. In addition to that, you get 30 Master Packs at a discounted price. Because those packs contain a majority of the cards in the game, there's bound to be a lot of cards you don't necessarily want or need, making for great dismantle fodder.
Stalwart Force is a great choice to pull from for 9/10 new players. It has a wide variety of decks that you can build from. Should an archetype from there catch your eye such as Dragonmaid, Sky Striker, Drytron, Eldlich or Tri-Brigade, it wouldn't hurt to do one or two 10x pulls.
Even if none of the available choices appeal to you, powerful staple options like Pot of Desires and Twin Twisters are still a great pickup. Not only that, they can even bridge to some of the Secret Packs you might be aiming for. There's a more convenient way to unlock them of course, but this is fine as well when you're just starting out.

Operating the Incinerator

Now that you have a bunch of cards to work with, it's time to dismantle the unneeded ones! While there's no 100% guaranteed way to determine what to dust, here are some general tips.

You're generally safe to dismantle cards from strategies that you don't plan on using or building for the account. For example, Tenacity of the Monarchs is a pretty good card for that deck but if you aren't pivoting towards that, it's fine to let go. Outdated generic cards that hardly see any play begin such as Scrap-Iron Scarecrow or Boogie Trap are solid candidates as well. Last but not the least, you can always reach out for help from more experienced players! The r/yugioh Discord server is available for this! I hang out there from time to time, so you can ask me too.

Crafting Time!

Now that we have all our preparations ready, it's time to start crafting! For a deck that you want to build towards, it's a good idea to check how they can be obtained by pressing the button. If it has a Secret Pack, you're in luck! Proceed to craft one copy of an SR or UR card, which unlocks the Secret Pack for 24 hours and gives you a free pull for unlocking it for the first time. My suggestion would be to craft SR cards that you need multiple copies for the Deck. That way pulling more copies will help you overall. In this example, we have SPYRAL Resort which the deck absolutely plays 3 copies.
Once crafted, spend your gems on the Secret Pack for a couple of pulls, usually 3000-4000 at max. This should give you the majority of what you're looking for. In some cases, decks have a lot more URs than usual so you're going to be relying on both generating and opening packs to pull through.
For decks that have to go through multiple Secret Packs, you want to spend your Gems and CP wisely so you don't overspend. Say you're building Zoodiac Tri-Brigade. A good idea would be to generate Drident and get a free pull off her Secret Pack.
Seeing as the strategy only needs a few Zoo cards, you can save the heartache of having to spend thousands of gems to get Drident. The other Zoodiac pieces are also easily craftable too. After that, you'd want to craft Ferrijit. 2 is often standard as the second one comes up a lot. Now you have plenty of gems to power through Echo Chamber Nation and get your key cards like Shuraig, Bearbrumm, and company! After that you want to clean up the remaining important pieces, such as fixing up your Extra Deck, getting Pot of Desires and Tenki for consistency, and so on.

Craft-only Decks?

There are some decks out there like True Draco which is perfectly fine and affordable but doesn't have any Secret Packs to work with. How does one go about it? In this case, we're going to have to generate the cards. Building a craft-only strategy still requires gems as you would need to do a couple of pulls to get the materials going. I don't recommend getting the Master Packs even if it says they can be obtained there, as that pack is too much of a gamble to work with. Only purchase it for the three bundles when starting out.

Craft Priority and Deckbuilding

Craft Priority will vary from deck to deck, but I'll be providing a basic outline on what to follow. As much as possible, you want to complete the remaining core cards of your Deck after some pulls. This is because they're often irreplaceable as the deck would need them to function. This applies to both the Main and Extra Deck respectively. In that screenshot above after crafting the Frogs plus pulling the Paleozoic cards, I would focus on crafting ED pieces such as Toadally Awesome and Divine Arsenal AA-Zeus.
Once you're sure the core of the deck is complete, you can then put your attention towards the powerful staple cards like Maxx "C" and Ash Blossom & Joyous Spring. In general, you also want to consider playing backrow removal if your deck has no native outs to it. The free Lightning Storm, Cosmic Cyclone, and Twin Twisters are all fine options. I'll be mentioning some budget going second cards in a bit.
Not figuring out the proper craft priority can become quite a troublesome issue. For example, trying to build Zoodiac Tri-Brigade and going ham on expensive URs, namely Forbidden Droplet and Called by the Grave. While they are incredibly powerful and help the deck out a lot, it's not going to be a good idea to start with them if it means your Extra Deck gets compromised. You can get them AFTER you're done building the core of the strategy. Cards like Impermanence are replaceable with budget picks such as Forbidden Chalice or Kaijus in the meantime, but ED pieces such as Drident or (the second) Shuraig are not.

Conclusion

And that wraps up our look into some tips and tricks with Generating and Dismantling cards in Master Duel! With the right decisions and smart crafting, you're able to build multiple competent decks as a F2P player! Until next time folks, Renren signing out!