I have played in auction drafts for some time and I love them! My #1 tip is go in prepared with a budget! Each position should have a value assigned that you are willing spend. Assuming you have $200 budget for your team, each position should have a value and every position adds up to $200. For example, this year, since RB’s are vital, I have $45 budgeted for my first RB and $35 for my 2nd RB. I think pull the average values from ESPN and the UDK and I map out my 1st, 2nd, 3rd, 4th, options within that price range. If you are playing with guys who dont have the UDK and may be drafting off ESPN vlaues you could get some value steals!
Nominating players should also be strategic. I like to nominate qb’s early, cause people will over spend on them. Then I move to players that share tiers with my players that i interest in to try and get people to spend more on them.
You also have to adjust on the fly, I have a spreadsheet that tracks my spending. Sometimes option 1 and 2 are gone and you may have to spend up to get that 3rd or 4th option. if you do, adjust you budget from other positions to accommodate.
But after all this, still #1 tip, Have a Budget and I would say have a way to track your spending so you stick to that budget!
Hope this helps.