Using ring buffers and per counters to see memory pressure ?

Look at a few different ways to identify memory pressure

(1) Ring buffers

http://thesqldude.com/tag/ring-buffer/

Which values of the returned results should I look at and how to compare them?

(2)

SELECT *
FROM sys.[dm_os_performance_counters] 
where 
 counter_name in('Page life expectancy','Memory Grants Pending')
 and [object_name] like '%Manager%' 

Same question - how to inprepet the results as good/bad