Guides for doing Google Ads for other clients (Lead Gen)

Hi Guys,

Is there any guide or forum which I can look up on to improve myself doing Google Ads for other service businesses.

Tried lurking around but most of the "good" guides seem to have been deleted, when I try to click on them through Google.

Currently experience issues on what bidding strategies to use and why my conversion rates are so low.

Therefore wanted to hear what your best experience have been to improve yourself doing Google Ads lead gen for other clients?