
My mentor (and now amazing friend) is the breeder of my dog which you will find is the most common source of a mentor. Other than that, in normal times, I would be talking to people in your breed at shows, get to know them, find someone who's dogs and breeding practices you like and, assuming they are willing, pick their brains. Show your dog as much as possible and watch others being judged to learn about the breed standard.
Every breeder has been a novice once so for me, as long as you have shown that you are extremely interested and committed to the breed you chose, are breeding for the right reasons, i.e. to improve the breed and not just for money, have good foundation dogs and a good setup, and have that experienced mentor in place who is willing to answer any stupid question you may have (trust me I've asked loads), then you are ok to breed.
There are some hugely experienced people on here (much more experienced than me) who may well give you a different or more complex answer but for me that's the basics.
Unfortunately though, at the moment you just can't get more involved in showing. Online shows just don't count I'm afraid