How can I make my banana bread more moist?

1. Turn the oven down by about 25-50F. Quite often, ovens just blast the heck out of baked good, especially smaller apartment ovens. Larger, more expensive ovens tend to be better calibrated and will produce the proper 350F temperature usually required for banana bread. A cheap oven, which is still fine for banana bread, will overshoot the temperature and kill your banana bread. Turn the oven down a bit, and if necessary cook for longer. I have even turned my oven cooler AND cooked it for 15 minutes less time than the recipe required.

2. Check at 2/3 time. Don't let the bread run through the entire cooking time before checking it. Always check early. For some recipes, I take the banana bread out at 2/3 recommended time!

3. Don't over-beat the mixture. Despite being called banana "bread" it isn't a bread, it is a cake insomuch as it is made from a batter, not a long-kneaded dough. If you start mixing and it seems already too dry - STOP - and add a few tablespoons of milk to loosen the mixture up. If it's too dry in the initial stages, it will certainly be dry later, but a dry mixture also causes you to push harder, thereby causing the gluten to harden.

4. Don't cut down on butter/fat. This is really what prevents it drying out. Use creme fraiche, more butter, a bit less flour...

Store banana bread is usually heavier on bananas (they have to get rid of them), and that will make for a heavier, moister, darker banana bread. I generally add at least one more banana than it calls for in the recipe, and you'll get a better flavor if you wait a while, and let the bananas get old and spotty.

While living in Michigan in the late 1970's, I baked several loaves of banana right before going to church to play the organ for the midweek service. I decided to wrap one of the loaves to give to the pastor and his family right after it finished baking. I wrapped the bread in foil and enclosed it in a Ziploc plastic bag.

The pastor's wife told me that the banana bread was the best she had ever eaten the next day, so I have continued to wrap the hot, freshly baked banana bread in some foil and enclose it tightly in a plastic Ziploc bag and put it in the freezer to cool down for a few hours.

If you don't mind getting a bit fussy, this advice from America's Test Kitchen should work great. I haven't tried it yet myself, I'll edit this answer when I do.

You can get 5 bananas (6 including a decorative one on top, not frozen or microwaved) in a loaf if you microwave them first (5 minutes on high, covered with pierced plastic wrap), freezing them accomplishes the same thing. The key step is to then drain them in a fine mesh strainer over a bowl. If using frozen bananas, put them in the strainer frozen, they'll drain as they thaw.

5 peeled bananas should weigh about 2.25lbs (1Kg). Strained, they should produce about 1/2cup-3/4cup of liquid (118mls-177mls) That's too much of the liquid to use in a loaf of bread (it makes the loaf overly dense), so ATK recommends reducing it to 1/4 cup. That syrup becomes the liquid in the loaf.

They also say that the bananas should be very ripe, but that there's really no difference in sugar content between very speckled and black. Either will work just fine.

For their Ultimate Banana Bread they use a full stick of butter, 2 eggs and brown sugar. They also sprinkle granulated sugar on top for a nice crust.

EDIT: I've done this now a few times. Yes, it's fussy, it also makes a great loaf of banana bread. It's very moist and very banana-y Of course the recipe is paywalled ATK Banana Bread Recipe, but they do offer a 14 day free trial.

First, I tend to wait 'til the bananas are completely black, and then freeze them 'til I have enough for a batch of bread baking, then thaw them the day before cooking. This ensures that the bananas are completely broken down (the freezing helps to burst any cell walls), freeing up all of the moisture from the bananas.

I also use a recpipe that uses molasses, which results in a very dense, moist loaf. Not everyone likes it though, as it can be a little bit heavy.

Yogurt. There's a recipe in a book I have called Baking Illustrated that uses it; I highly reccommend picking up that book, as they discuss what each ingredient does in the bread. I believe their recipe calls for 1/4 cup of plain yogurt added to melted butter, bananas, and egg for the wet ingredients alongside the usual dry ones.

I only use 2 bananas but add 1/2 cup plain applesauce and 1/4th cup half and half. Comes out very moist and yummy.

I use olive oil. You can use light or extra-virgin olive oil. The olive oil will make any bread cake moist. Other things I do for my banana bread are adding a little molasses, just a little bit more sugar and vanilla flavor and more bananas. I usually let it cool a little and then wrap it in aluminum foil.

I use a small box of instant vanilla pudding in the batter and my bread comes out moist every time

I find when I add apples it makes my breads and cakes very moist.