There are several ways that you can achieve getting the most out of your money: First there's the 'Free Factor' to consider, in which not a dime has to be spent. Then there's the 'Pricing Factor' where you research and determine where the bulk of the money actually goes to. Lastly there's the 'Emotional Factor' where your heart leads you to what would financially be worth the most to you.
Free Factor examples - Donating blood, spending time with someone who is house or hospital bound, giving unused or unwanted foods to someone, having a good long visit with someone who is lonely, giving someone a genuine compliment, helping someone with their groceries, reading a story to a little one, holding someone's baby, taking someone's cart back for them, watching someone's kids, driving to someone's house that doesn't get many visitors, sharing your talents and skills for someone else's benefit, truly listening to those that are speaking to you, volunteering your time in a play/benefit function/shelter etc., going carolling, giving a hug, giving a smile, making a phonecall to a business just to give a sincere compliment, visiting with someone at a grocery store until they decide they need to rush off, painting a little girls nails, making someone laugh. There are many many more that fall into this category
Pricing Factor examples - There are a great many charities out there, some of which once personally investigating give not even 50% of your proceeds to the actual persons in need due to many of them being run by paid employees. Obviously getting the most bang out of your buck in this category would indicate that you would have to give to a charity or cause that runs off of unpaid workers so the proceeds go straight to those in need. Here is one such place where 100% of your money will go to the cause you indicate: http://www.ldsphilanthropies.org/humanitarian-services.html
Emotional Factor examples- This one truly gives the most bang for your buck as your heart is what leads your decision and therefore gives you the satisfaction of love and peace from it. These are causes where family, friends, and community play key roles in the development of a cause that's ever so dear to you or them. Though they may or may not be free, and may or may not have unexpected additional fees, you still feel you got the most bang for your buck.
Always remember this Christmas season:
"...the worth of souls is great in the sight of God" -D&C 18:10
If you give of yourself in any way you can that "buck" can never be wasted.
Those that get the most bang for their buck have learned that true wealth comes from giving away your riches to those who are less fortunate so that they too may share in the spirit of love and thanksgiving.
Heaven's slice is charity.