More and more things are going out to competitive tender, particularly for work in the voluntary sector which often used to be given in the form of grants. Bidding can be a long drawn-out process and take up a lot of resources, so it's important to decide which tenders are worth going for – and whether it's better to spend a lot of time on a few tenders or go for all of them (because it's a lottery anyway).
While it's not simple to decide and you need to think about your own strengths and weaknesses, it's generally better to concentrate on those tenders where you have some unique selling point (special knowledge, very relevant experience, personal contacts, local network) because in these days of austerity a lot of people will apply. There are no silver medals, and anyone with some specific edge is going to win over an average proposal. On the other hand, you need to put some speculative bids in because it helps with marketing – and you do win some of them.
Whatever you do, you need a system and a way of guessing the chances of winning so that you can put appropriate resources into bidding rather than implementing projects. We've systematised this – either you can download a free tool to estimate chance of winning (you have to register first) or you can buy a toolkit which looks at ways of dealing with uncertainty.