It takes a lot of practice and trial and error I think. Some recipies do great with some ground flax seed and hot water mixed together, others with egg replacer ( a potato starch) and the baking powder/oil mix. or mashed bananas.... try your local library for allergy baking cookbooks.
There's a cookbook called Bakin' Without Eggs by Rosemarie Emro. I bought it when dd1 had an egg allergy. I recently sold it on the TP. The recipes were good, considering no eggs. Before I sold it I wrote down the recipe for chocolate chip cookies, which is a great cookie recipe, and for eggless pancakes. I can post them if there is any interest.