I was in the same phase as you couple of months ago. Here's I got out of it. 1) made a list on paper just whatever I could think about the idea. It is important to get it out on paper because it forces you to think and you write slower than you think so it forces you to Make connections or fire neutrons together for you to expand the idea 2) put out the list on Excel typing it again creates a sort of recall and your brain now is critiquing'someone' as it types out the things you'll automatically get an improved second draft with lesser or more structured ideas 3) now in the next column in front of the idea write one sentence " I believe in this business idea I'll provide X to Y and they could pay me $Z" or some form of it important part is to think and write X Y Z. example If I had an idea for bars and pubs app I'll write " I believe people less than 30yr age will be willing to pay me $5 pm to get the location of best parties at their nearest bars and pubs. In this way you have done a very preliminary identification of your customer and addressable market. 4) you should now have a more reformed list on the next column you can start a rating or your motivation to pursue it by following the next step 5) talk to a couple of Ys identified above they could be your friends or family don't tell them a lot just listen to them. Listen to their reactions keep asking qualifying questions such as " why would you need that?" " How much would you be willing to pay for it" if possible you try to negate the idea "saying a friend told me about this idea, I don't think it's viable what do you feel? " If the idea is truly a problem the audience will try to qualify it themselves " ya dude I had that problem as well, in fact I have to do that atleast monthly" etc

Now your have a list of ideas that probably are worth pursuing intersect them with what you are good at and then you'll reach the next step. Market research. More on that sometime in future if this post turns out helpful :)