To star with, give live to your ideas. Be critical and look at apps you use daily and see what could be improved. Simulate that as a real project and client to work on the project. Have your friends or senior family members to play the personas or act as stakeholders. Time box the project. Work on 2-3 good ideas and prepare case studies. Technology & priorities keep evolving, so there isn't one rule that apply to all. As far as opportunities are concerned, there are many. Scout on LinkedIn, other than UI/UX also look for IxD, UI Evangelist, Use Interaction Designer, UX Visual Designer... The list goes on. Basically, get your fundamentals right. Focus on research and 'probable solutions' than one solution.