Auction Draft Help Please!

This is my first Auction draft. Ive done a couple mock drafts and im just not sure how much to spend and where. Also, which players are best to nominate?

This is a 12 man PPR league. the Roster Layout is:

1 QB (4 Max), 2 RB (8 Max), 2 WR (8 Max), 1 TE (3 Max), 2 Flex and six bench spots