Very low DB Buffer cache hit ratio, how to improve it?

Hi all, I'm a total beginner when comes to performance tuning the DB. Recently my company just implemented a third party monitoring software to monitor all our hardware & software. I notice on my Oracle DB there's an alert thrown, the alert is referring to the DB Buffer cache hit ratio. The recommended value should be 99% but it's currently at 41%.

I then ran the below script on the DB directly.

SELECT ROUND((1-(phy.value / (cur.value + con.value)))*100,2) "Cache Hit Ratio"
FROM v$sysstat cur,
    v$sysstat con,
    v$sysstat phy
WHERE cur.name = 'db block gets'
AND con.name = 'consistent gets'
AND phy.name = 'physical reads'