Add gluten. You can get gluten in many supermarkets. I use Bob’s Red Mill brand, which comes in a small clear bag. Cost a few dollars.
Here is what I do, and I get good rising:
Warm the water until it feels warm on the wrist. It’s like testing a baby’s bottle, but a little warmer. If it hurts your wrist, add cold water. Add a teaspoon of sugar for every cup of white flour that you use, 4 to 5 teaspoons for every cup of whole wheat. Mix sugar in water. I put mine in a cup and prepare the flour and salt in a bowl or pot.
Use about a teaspoon of yeast for every 4 cups of flour. Mix the yeast into the sugar water and let stand for 15-30 minutes. It should foam on top.
The flour: Use bread flour, which has extra gluten, or use regular flour and add a teaspoon or two of gluten (see above). One teaspoon of salt for every 3 to 4 cups of flour. Maybe a little oil. Basically, I make a water challah.
Add yeast-water to flour mixture and add water as needed. If too gooey, add flour. I think I use one cup of water for 3 cups of flour.
Let rise for 2 hours or so, punch down, and shape. Turn on the oven for two minutes, so that it’ll be warm. Make sure oven is off and only lukewarm. I like to egg wash the challahs at this point because painting the egg on after they rose can partially deflate them.
Put challah in lukewarm oven and let rise for about 30 minutes. It they rose well, take out, turn on oven, and put back inside when full temp is reached for baking. If they need some more rising, give them a little more time, say 15 minutes. Alternatively, you can let them rise at room temp for 1.5 – 2 hours.
Don’t let to over-rise. They will get too big for themselves and collapse.