First offseason coming up soon
 

...and I wanted to try to get a grip on how to progress.

I have the historical draft file from the site. But I'm not sure exactly how to input the right years draft players into the game (and at what point). Again, this may be very obvious once I get to that point but we just finished week sixteen and trying to get ahead of the curve.

Any other nuggets of interest that I should be watching out for heading into the offseason that you've learned the hard way that would be beneficial for me to avoid?

Thanks!

After you get to end of season, after the staff resign you can press a button: "Import draft" ... that should work out fine.