How to build a portfolio

We've covered quite a lot of ground in our series on investing for beginners, and we now know the mechanics of actually getting going. Time to get on to the hard question, then, which can stump even the most hardened of investors: 'What shall we buy?'

What is the best number of different shares to own? How much should I diversify? Should I go for capital appreciation or income? How about growth versus value?