I'm interested in learning more techniques, tips or strategies that you use with a tarp with no dedicated poles or trekking poles.
I personally don't use trekking poles much, and I don't carry dedicated poles for my tarp. I've done four solid trips in this way recently and really like it. For me it fits in perfectly with my hiking style of using/having less gear, and using more creativity/skill to accomplish the same task, in this case shelter supports.
One of the hardest situations I've encountered is above treeline when there are no downed sticks, trees or much of anything for that matter. The second pic here shows one way I pitched my tarp in such conditions (not above treeline in this case, but using similar supports as avail above treeline), in this case it was because of high wind and the rocks provided the best natural wind break.
Pics from Section B of the PCT May 25, 2008 (full trip report to come, tarp is 9' x 7' x 4' 6" etherealgear.com silnylon):
Warner Springs area (body shielding downed stick for front ridgeline, treewrap for foot ridgeline):
Fobes Saddle, San Jacinto Wilderness (crazy high wind speeds):