Need advice on the best way to pick up short hauling clients. 

I trained professionally for 15 yrs but I'm a teacher now so have some time on weekends to haul from Oklahoma to wherever, up to 100-400 mile trips. 

Going through a divorce and needing something to do. 
(and helps expenses on my truck and trailer)

I am excellent with trailer loading/hauling and have a client in Kansas that I hauled for for 3+ years for reference. 

Thanks for any tips/advice!

Sounds like an awesome excuse to hang out at Heritage Place sales looking for horses to haul. 

There are FB pages.  I've had several colt buyers try YouShip over time.  Not saying I endorse that to my buyers because there are some wacko haulers on there, but it might be okay from the hauler's perspective?  (The last one of those that showed up here had half a trailer of mules on board, a farm truck instead of a pickup, no cap on the fuel tank and it was raining.)

You can set up a website too.  And of course, word of mouth.  Tell your friends.

Best of luck!