The source is of high quality if its content is appropriate, up-to-date, unbiased and comprehensive enough. Prefer original sources, not the bulletins or summaries of them..
For example, take a look at the University of Tampere Library and LUT Academic Library's guidelines on evaluating information sources.
Check this video first!
Assessment belongs to every stage of the process. This figure reminds of assessment and evaluation in the different situations.
Source: Ifla Repository: How to Spot Fake News - COVID-19 Edition