You can buy bitcoin (BTC) on centralized exchanges, and peer to peer (p2p).

A lot of people prefer p2p BTC buying solutions over exchanges because:

There are multiple peer-to-peer BTC buying solutions, such as Bisq, Robosats, hodlhodl. Every solution has its own benefits.

bonds*: they are payment guarantees to eliminate bad behavior. In case of bad behavior, the bonds can be lost.

escrow*: During these transactions the sellers have to deposit their BTC into an escrow, that makes sure for the BTC buyer, that the seller has the BTC. The BTC can only be released by the seller, but he can only send it to the buyer, or with a problem resolution, it can be released back to him. This escrow makes sure, that the BTC is available, can be sent to the buyer's address when the buyer sent the equivalent amount of fiat to the seller, and the seller can't behave badly.

The total sats amount is FIAT / BTC market price, because the premium goes to the seller.

The usual payment methods are bank transfers, gift cards, and even cash is possible, but then you have to meet the seller. As p2p BTC buying is about control and privacy, it is better to try to use more private payment solutions.

One of the most private payment solutions is cash, but for that, you need to meet in real life. This can be inconvenient.

The other most private solution would be buying gift cards in a shop with cash also. The disadvantage of this is, that your money is locked in a gift card, and if noone takes it, either it is stucked in the gift card, or you have to use the gift card.

The second most private is buying gift cards online, but in this case, the gift card is already traceable to your account. But still you are not giving your bank account to anyone, and the gift card seller has to be contacted to make the tracing possible. In some cases, your account name will be shared when you redeem some gift cards. But you can setup a new account with a fake name, and then only that will be shared. But when you use your bank card with that account to buy the gift card, then you can also be connected to the account. But still it will require more work for traceability.

The least private solution is using a bank account, because then you have to share your bank details.

The second thing to consider for selecting a payment method is disposability. If you buy BTC regularly with your bank account, and it won't be preferred, then your bank can either deny these transactions, or lock your whole account. This can have bad consequences for you.

So if you prefer to use your bank account, it is advised to use a separate bank account for this, not your main one. In this case, if anything happens, your main account is not effected. You can use an older bank account you don't use, or create a new one with Revolut, Wise, etc. Usually it is advisable to select a new bank account that supports fast wire transfers, because people usually go for those orders.

The third and most important thing is, that you need buyers/sellers for your orders. You can select any type of private solution, but if no one is willing to use it, you won't be able to stack your sats.

Depends on the location, but usually bank transfers are the most salable, but the least private. People prefer it, because then they get FIAT directly, that they can spend on anything. Gift cards can only be spent in the shop the card is from. Also cash is less preferred, because can't be done over the internet.

They have to lock the BTC they sell in escrow before you send your FIAT, and then they can only release it. Or if there is a mutual agreement, they can get it back. Until they don't lock it, the chat won't open up, and you can't send your FIAT.

The market price is used, and the premium is added on top of the market price you set. This means, you don't specify a specific market price, but a premium that you are willing to pay over any market price.

When your order is taken, and the seller locked his bond and escrow, you can either give a lightning invoice that the seller will pay, or a BTC address where the on-chain BTC will arrive. In case of on-chain BTC, you can even define the mining fee.

They are incentivized to do so with the premium that buyers are willing to pay for p2p or non-KYC BTC.

It depends on your order. If you use commonly used payment method and set a reasonable premium, then it can be really fast. But if either you select a not popular payment solution or too low premium, it can take even a day or more to find someone for your order.

For the premium, you can check the suggested premium on the chart view.

For the payment methods, you can check the currently available BTC sell orders, because you want a BTC seller to match your buy order.

Usually BTC sellers are creating orders with higher premium because their goal is to sell their BTC for more profit. Buyers are the opposite of this, and want to get cheaper sats. Due to this, sellers are creating orders with higher than necessary premium, in case someone buys them, but in the mean time orders with meaningful premiums are also getting accepted. So if you don't want to pay too high premium, you most probably have to create your own order.