Some of the BEST practices for Test ESTIMATION is

Add some buffer time: Having a buffer time is always an advantage, it may help to deal with a delay CAUSED due to unexpected reason like talented member quits the job suddenly,

Account resource planning in estimation: Make sure that your estimation is realistic, and considered important factors like availability of human resource, resource planning,

Use the past EXPERIENCE reference: Through your past experience try to avoid all the obstacles or possible hindrance that are most likely to happen

Stick to your estimation: Estimation is not FULL proof, it may go wrong also. In the early phase of the project, you should re-check the test estimation and if required make modification as well.

Some of the best practices for Test Estimation is

Add some buffer time: Having a buffer time is always an advantage, it may help to deal with a delay caused due to unexpected reason like talented member quits the job suddenly,

Account resource planning in estimation: Make sure that your estimation is realistic, and considered important factors like availability of human resource, resource planning,

Use the past experience reference: Through your past experience try to avoid all the obstacles or possible hindrance that are most likely to happen

Stick to your estimation: Estimation is not full proof, it may go wrong also. In the early phase of the project, you should re-check the test estimation and if required make modification as well.