What are some steps that scientist can take in designing an experiment to avoid false negatives

Hello.

False negative is a condition when you got a negative result that is inncorect.

To prevent false negative occur, first you need to use golden standard test or a test with high specificity.

You can do multiple tests to ensure the specimen is negative and using a positive control to make sure the results are correct.
Have a nice day

They can run the test more than once to confirm their answer(s).