If you want to build an app for traders, start trading yourself. If you want to build an app for mass email campaigns, look for web marketing work to pay for so

If you want to build an app for traders, start trading yourself. If you want to build an app for mass email campaigns, look for web marketing work to pay for some R and D. Approach things practically, keeping the theory to a minimum (though it's vital too). Really ask yourself who you have access to (friends, colleagues) and what you are passionate about. Chances are that's the domain your best ideas will apply to.