I don't think it's subtle at all. Pick existing popular technologies / frameworks. If you like to gamble a bit, pick those that you see growing quickly. Invest

I don't think it's subtle at all. Pick existing popular technologies / frameworks. If you like to gamble a bit, pick those that you see growing quickly. Invest time in learning new stuff (ideally, on an employer's dime) throughout your career. If you don't care about being on the 'bleeding edge', you really don't have to think about it too hard and you'll have plenty of job opportunities.