You gain 1 Strategus Ticks for every Exp+Gold tick ingame. So you gotta play cRPG to gain them (not DTV or Strat Battles).
What they are good for:
When you recruit troops (Troop cap to a higher amount then you got) you loose 1 tick every hour and gain 1 troops therefor.
When you dont recruit troops you gain 10 silver (strat gold) every hour and loose 1 tick therefor.
When you dont have Strategus ticks, you cannot recruit troops.
Not sure amount the exact numbers, but those are my best thoughts.