This is an exercise in creating maximum leverage for small to medium sized donations and an exercise in showing how just about any citizen in an industrialized country could save at least one life each year in their spare time.

Suggested Prerequisites

• An annual donation budget or spare time to generate some extra funds. 
  Personally, I’ve used the Uber Driver app to take advantage of the occasional lucrative promotion or peak event demand in a nearby city. Also I'm a US resident, so I can sign up for new plasma donor programs at 1-2 new centers a year that pay an initial $700-$1200 for 8 donations in the 1st month. These centers include places like CSL Plasma, Biolife, Grifols, Biomat, Freedom Plasma, Kedplasma, Immunotek, Gcam Plasma, Octapharma Plasma, and BPL Plasma. 
  People with different resources and skills may have other ways of generating their initial donation funds, but these are just some examples if your current job doesn't include a high income.
• A credit score of 670 or higher.

First Multiplier: Credit Card Sign-Up Bonuses For Donations (1.1x to 1.65x)

If you have a 670+ good or excellent credit score, then you can qualify for several credit cards with sign-up bonuses ranging from $200 back on the 1st $500 spent to 10% back on several purchases for the 1st year (including some sites where you may make an online donation). All this requires is the good credit score, reading some sign-up bonus conditions to ensure your donation transaction(s) will qualify, and time to fill out the paperwork & unfreeze your credit on your credit site(s) like Experian or Transunion.

In addition, some of these cards offer referral bonuses for people who sign up with your referral link (Ex: https://capital.one/3y2YbGv).

So if you want to coordinate with some of your friends or with other Effective Altruists in the community, then you can use these referral bonuses to multiply your funds even more than the 1.1x to 1.65x listed in the section header.

For more information on credit card sign-up bonuses and avoiding any pitfalls, check this more extensive blog post on the topic.

Second Multiplier: Donation Matching Events (1x to 2x)

Here donation matching events mean things like Every.org's occasional matching events. These are events where matching funds could go to less effective charities or to more effective charities, so securing these matches for effective charities like GiveWell / Malaria Consortium / Against Malaria Foundation / New Incentives / Evidence Action / Giving What We Can / The Life You Can Save / 80,000 Hours / Rethink Priorities / Giving Multiplier is not a gimmick and truly adds more funds to more effective charities.
There are also several, usually end of year / holiday season, donation matching campaigns for various effective charities. These campaigns are less convincing because the matching funds would likely be donated to them anyway, but some may be encouraged by them. In 2024, The Life You Can Save has a few effective charities, like Evidence Action, with matching campaigns here.

If you apply for a credit card with a good sign-up bonus, then you can use that card for your matched donation(s) to combine the card sign-up bonus multiplier with the donation matching event multiplier.

Third Multiplier: Employer Donation Matching (1.1x to 2x the donation transaction amount)
[*Will likely add to, but not multiply with a donation matching event multiplier]

Some organizations have charitable donation matching programs for their employees. Most employer programs will match 50%-100% of their employees’ donations within certain limits like donation minimums and/or maximums. The employees often just need to check that their donation will qualify under their organization’s policies and submit a donation match request with documentation of their donation transactions. 
If you plan to combine an employer donation match with donation matching events, make sure to check how the event site processes & documents the donation transactions. If the donation is made to the event site or some intermediary, make sure your employer‘s donation matching policies accept donation documentation from such a site or intermediary. For example some organizations will match Facebook donations, while others may not.

Fourth Multiplier: Donate to Giving Multiplier's Matching Fund (1x to 2x)

Giving Multiplier is a site that runs a kind of year-round matching program to encourage people less familiar or less engaged with EA to donate more money to GiveWell charities. The site allows people to bundle a donation to their favorite charity with a donation to an effective GiveWell charity and Giving Multiplier will match the portion of the donation going to the GiveWell charity. Depending on how many people are encouraged to donate more to effective charities, Giving Multiplier could direct anywhere from 1 to 2 times the money sent to their matching fund to effective charities.

By using the sign-up bonus credit cards to donate to Giving Multiplier’s effective charities matching fund & submitting receipts to an employer matching program, you can stack the card cash back multiplier, employer match multiplier, and a Giving Multiplier fund multiplier.

For more on Giving Multiplier, see this update from the founders on the EA forum and this critique from another community member.

Conclusion

Lowest Multiplier Stack Estimate: 1.1Card * 1.15GiveMulti = 1.27x

Likely Multiplier Stack Example: 1.25Card * (2Employer or 2GiveMulti or 2MatchEvent)  = 2.5x

Highest Multiplier Stack Estimate: 1.65Card  * 2Employer * 2GiveMulti = 6.6x

Even if someone only had $2000 to donate or only 40-60 spare hours to generate the equivalent funds, they could use some method of donation multiplier stacking to direct enough money to effective programs to save at least one life per year.