Google Ads Lead-Gen Optimization

My Search-Network campaigns are active inside my Google Ads account, but lead volume is lower and cost per enquiry is creeping up. I need your help to retune everything so the account is firmly focused on generating qualified leads... (Budget: $10 - $50 USD, Jobs: Digital Marketing, Google Ads, Google Adwords, Google Analytics, Internet Marketing, Lead Generation, PPC Marketing, SEO)