Chiggers, ticks, poison ivy, etc...all are real downers and potentially expensive to deal with depending upon allergies, skin types, severity of exposure, etc.
Our approach for the last several years has been to always wear long pants(jeans) and either tuck the pant legs into the top of a mid calf rubber work boot or use duct tape and tape around your ankles to close off the lower pant leg "avenue".
We also apply Off, with deet, and/or Skin-So-Soft to our skin, in particular, our legs, hands/wrists and around the "belt area". We also use permetherin based sprays on our outer clothing, particularly our pant legs and boots.
If we take these steps without shortcutting them, then we have not had any problems with the "big three"(ticks, chiggers and PI.). And others have said, a good shower after being outside is also a good preventative measure.