I advise highly against a snake style draft and also excluding rookies for the main draft.
A dynasty startup should be auction style only and should include every player. No one earned a draft pick, why should a few teams get the best rookies because they got lucky with a random draw?
Who you draft effects your team for years to come, you shouldnt be “stuck” with a team based on a draft pick.
think about it, how much more of an advantage would someone have if they got lucky enough to draft top 3 in both the vet draft and the rookie draft?
Put everyone on equal ground, if you want a guy then pay for him. dont be automatically excluded from getting gurley, barkley, etc because you get the 7 pick or something like that.
The biggest thing ive learned in my 10 years of dynasty is dont just focus on the future. If you always look into the future you can never be looking at the now and may never win your league. You need a good mix of young talent and established studs and consistent depth.
Fear of making moves because you have a guy that you think is going to be a stud in 2-3 years will hurt you. (this is more for when you are making roster decisions in the future). Keep this in mind when you draft, dont fill your team full of high ceiling 1 year wonder type of guys, you need some good vets to anchor your team around.