When a source is well written it will "signpost" important evidence used to support an argument.

Examples of such signposts include:

• An important issue is …
• This illustrates ...
• This is demonstrated by …
• There are three reasons for …
• Major discoveries include …
• One example is …
• In contrast …

You can use these signposts to identify what the writer considers important to their argument, or as evidence supporting their point of view.