You should say:

• What the invention is
• What it can do
• How popular it is
• Whether it is difficult or easy to use
• And explain why it is useful

Sample Answers: https://ieltsquangtri.com/describe-an-invention-that-is-useful-in-your-daily-life/

You should say:

• What job it is
• How you know about this job
• What types of people do this job
• And explain why you think this job is useful to the society

SAmple Answers: https://ieltsquangtri.com/describe-a-job-that-is-useful-to-the-society/

You should say:

• Where is it
• What the place is like
• When you visited there
• Who you went there with
• And explain why you would recommend this place to others

Sample Answers: https://ieltsquangtri.com/describe-a-place-you-have-been-to-and-would-like-to-recommend-others-to-live-there/