How to get the role you want (assuming it isn't Support)

Do you put Fill or Support as your secondary.

Yes, it's a lower queue time, but that is only because it spends less time trying to get you into your primary before it switching to putting you as Support.

Do not put Support and then beg whoever got your preferred to switch with you.

If you really want top, ADC, or Jungle, put mid as your secondary. Since Mid has a higher queue time, it's far less likely you'll get it instead of your primary.