Don't leap before you are ready. When you're under pressure to deliver, the temptation is to get the ball rolling'. The ball is big and heavy and it's very, very difficult to change its direction once it gets moving. Spend some time deciding exactly how you're going to solve your problem in the most efficient and elegant way.
Try and deliver happy surprises, not unpleasant ones. By promising low (understating your goals) and delivering high (delivering more than your promised) you:
? Build confidence and get a receptive atmosphere
Consider: if everything goes right you will finish early everyone will be happy; if something goes wrong you might still finish on time ; if things goes really badly you might still not deliver what you anticipated but it will still be better than if you over-promised!
Most problems worth solving are too big to swallow in one lump. Any serious project will require some kind of decomposition of the problem in order to solve it. You must pay close attention to how each piece fits the overall solution. Without a systematic approach you end up with a hundred different solutions instead of one big one.
You have an end goal in mind. You need to work methodically towards the goal and provide leadership (make decisions). This applies whether you're a senior project manager with a team of 20 or you're a lone web developer. Learn to use tools like schedules and budgets to stay on track. Consistency is what separates professionals from amateurs.