Here is my foolproof recipe - makes enough for two greedy adults:
Using a dessert spoon, put 6 very heaped spoons of flour into a bowl.
Crack one large, or even two medium, eggs into the bowl.
Add enough milk so that you can mix all the flour in, but leave it thick.
Give it a good stir to work out any lumps.
: Add soda water (or even if you only have sparkling water, add 1/2 teaspoon bicarb to the mixture) in smallish amounts, stirring (or beating, or whisking or whatever works for you) until you get to the right consistency - you want it to be runny and smooth but not too thin. Enough that you can lift a spoon and pour it off, but it's not like pouring water - think pouring cream consistency.
If possible, and not too hungry, leave to stand for at least half an hour. Then give a good stir before using.
To cook, heat frying pan. Non stick is best. Put in tiny amount of cooking oil (I actuall smear oil on using a piece of kitchen towel so I don't get any actual oil in the pan, just a coating). When pan is hot (more pancakes are ruined by a lukewarm pan than anything else), pour batter in quickly, twisting pan to get the batter to spread out. As soon as the batter covers the pan, stop pouring.
You should be able to turn your pancake about 30 seconds later.
Then serve another 30 seconds later to a grateful and awe-filled audience.
HTH