The Binding of Isaac: Rebirth

Unlock The Keeper

To unlock the keeper you have to donate 1000 coins to the greed machine at the end of a greed game, which is easier said than done. But, there are ways to speed up this process, and know that the greed machine might break after a game.
Firstly you should know that constantly donating on one character (i.e. Azazel) will increase the chances of it breaking earlier through donation, for example, lets say you had 99 coins when you beat greed the first time as Azazel and you donated all 99, you will probably have a 2% chance of it breaking (maxing out at 20%) this will carry over if you do another run with Azazel, and only get more and more likely to break with less coins donated. So your best choice of action is to try to donate around 100 on each character, as apposed to trying to donate all 1000 on a single character. It is possible, but much more time consuming than using each character once or twice.
There are also some good tricks to help you donate around 225 coins in a single run, by getting a blank card, a two of diamonds, and car battery. If you donate 74 coins (getting you down to 25) then using the blank card, that'll send you up to 99 again, then donate another 50, and then use the actual card itself, then donate the other 99. But the chances of the machine breaking increase with every coin donated.
There are also methods that will allow you to fix the machine after it has broken with the glowing hourglass.

The donated coins carry over to each characters machine, but the chance to break does not. The machine is fixed after each run, but the percentage of breaking will remain locked on a character.

The easiest ways to complete this are with room based items, like the shears, which will make your head float, but your body attack everything near you, just make sure you stay in that room and don't leave until all waves are done, as this will end the effect of the shears.

This is kind of going to be an add on to the first solution.
In my opinion Lilith is the easiest character to beat greed mode with, the stratagy is to use your box of friends item before starting the waves of enemies and after 4 waves using it again and after another 4 waves using it again and then you have 4 tears coming out at once and you can easily clear rooms.
Just make sure to stay in the main room until you have beaten all the bosses you want to beat (its up to you if you want devil deals) this is so you don't lose all of your followers by leaving the room.
The car battery is one of the most useful items to get with her because you can bring out two friends each time you use your item essentually doubling your fire power, the car battery should not be passed up.
Lastly though she is the easiest character to win as. You will still have to change characters a lot so the greed machine doesn't break as easily causing a lot of anger.

I'm not a fan of Greed mode, and luckily there's a few tactics on how to cheat it. All you need is patience and a whole lot of luck. And patience. But when it works you'll become an unstoppable God, with plenty of money at the end to donate to the machine on each run. Not to mention unlocking some really powerful items for the other modes.

Step One: Get a Blank Card (https://bindingofisaacrebirth.fandom.com/wiki/Blank_Card)
Blank Card is unlocked by beating Isaac with the Eden character. Once it's unlocked in your item pool get ready to start Greed mode, and then get ready to restart that mode dozens of times. You want to enter the first shop, see if Blank Card is buyable, and otherwise restart.
When you finally see the Blank Card (which normally costs 15 coins or 7 if you're lucky) you need the coins for it, so beat the eight normal waves. Buy the card and move on to step two.

Step Two: Get a 2 of Diamonds (https://bindingofisaacrebirth.fandom.com/wiki/Cards_and_Rune...)
If you're super lucky you can find this sometimes in the Curse Room (the room with the spike doors), so always check that room first when you have the Blank Card. Otherwise you need to pray to the shop gods again. Often the shops will sell cards, and since the shops restock automatically in Greed Mode you can buy a card and hope the next one is a Playing Card (see the link for how those cards look like if you're unsure), and then again hope that it's a Diamond and not one of the others. When you finally have both a Blank Card and a 2 of Diamonds you can move on to the final step.

Step Three: Find a shop with Lil' Battery (https://bindingofisaacrebirth.fandom.com/wiki/Batteries#Lil....)
Again, the shops will sometimes sell batteries, which will also automatically restock. So when you finally have all three ingredients you can go nuts. Double your money with Blank Card, buy a new battery when needed, and repeat. And then you can buy all of the (passive) items the shop sells, which it will restock endlessly. You can keep this up until you're bored or scared that the game will crash due to everything happening on screen. But by the end you'll be so powerful that nothing can stop you, and as long as you have 99 coins with a charged Blank Card after beating the final boss you can potentially donate 149 coins to the machine as well.

Some obvious tips
* Greed Mode is no joke, and things can go south very quickly. I've failed plenty of runs with step one and two completed, only to die before I could power myself up by finding a battery. And yes, it's very annoying when it happens. So play carefully.
* Use your character's strengths to your advantage before you're powerful, don't relax until you have everything in place.
* Destroy poop and treasure rocks, explore the curse room (unless you're low on health), anything really to keep you in fighting spirit.
* Some shops will let you reroll the items for the price of a couple of coins. Don't be dumb (like I was plenty of times) and reroll too many times, making you too poor to actually buy the item you want.
* It's better to save your money for 2-3 floors when you're hunting for 2 of Diamonds / battery, rather than rerolling the shop. The next shop might have the item without you spending coins for it.
* If you only have 7 coins or less it's no point in buying the battery, since you won't have enough money to buy the next one after doubling your coins. Move on to the next floor instead in that case.
* You want to avoid buying the following items, which will sabotage this strategy: "Missing No.", "Little Baggy", "Chaos", "Marked" and "? Card".
* Play some other mode in between all of this, to keep you sane.
* And yes, I do prefer this method over actually playing Greed Mode normally.