[jbjbjbjb]

Checklists work well to make sure you’ve accounted for everything you know will usually come up but often get forgotten. These are things like the code cleanup and refactoring.

You should try to go quite granular rather than broad when coming up with your estimates. Better to have lots of small tasks, it shows you’ve put enough thought into the estimate and you have enough small tasks that estimation errors will average out.

You should also consider the level of detail the requirements have. For example if you don’t have wireframes there’s a lot more uncertainty than if you do. You should put confidence intervals or buffers to account for that.

It’s always better to overestimate than underestimate. There’s an asymmetry here where underestimating can cause chaos and overestimating is much less painful.

I recommend reading Software Estimation by Steve McConnell.