More often than poor planning or lack of skills, projects fail due to vague ideas about their goals and ways of measuring success. Your project's goal should be feasible, comprehensible, manageable and beneficial. Agree on the metrics with your customer.
Your time and financial plan must be based on a detailed survey and comparison with similar projects. Numbers can never come out of the blue.
The project manager must communicate with his team, the customer and the other involved parties. All these people need to know how the project is developing, if something has changed, what the actual risks are etc. A lack of communication can't be excused.
The project's scope can't be defined during the course of its implementation. It must always be agreed on in advance. You should also agree on a binding procedure for the possible expansion of the project.
Every project manager should listen to the comments and suggestions of his team members. If you think you know everything, try to think about it again.
Closely monitoring every step of the project team is another extreme. Micromanagement will costs you the confidence and motivation of your people.
Project management software is very useful, but only as a tool it can't solve problems. Problems have to be solved by people, software can only help.
The best process is simple and includes clear steps that need to be done and outcomes. All your people should therefore know what and when it must be done.
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