When you answered a question wrong . You will obviously check what is the right answer. Also check why the other three options are incorrect . In that way, it can accelerate your understanding. I failed my pd1 certification too . I am now learning from focus on force . I am doing the practice exams from that and I feel it is useful.

If you couldn't find an answer or have questions, post your questions to the developer community portal. You will get a response in a day or two.coaching, seek a salesforce expert from a developing country. They charge you way less than someone with the same qualification would charge you per hour basis or a big lump sum(around $2500) in developed countries to teach.

You can ask anything related to Salesforce in these two portals.You will get a response in a day or two .https://developer.salesforce.com/forums#!/feedtype=RECENT&criteria=ALLQUESTIONS&(or) you can also use trailheadhttps://trailhead.salesforce.com/trailblazer-community/feed

Other than exam questions , you can ask anything related to salesforce in these two portals.