There are nine common mistakes of project planning in the software development. Every project manager should care about those mistake before starting of planning. The following nine mistakes are:
1. Not planning at all
2. Not planning enough
3. Default caused by risk events
4. Reusing the same plan for different projects
5. Applying "standard" plans
6. Let plan to be different from reality
7. Detailing too much at the beginning
8. Planning to recover later…
9. Don’t consider mistakes that we have done