I am a big fan of Garda Hitch with rings. Use it exclusively with three (3) HH models. I sing its praises whenever I can.
I echo MacEntyre on how to take it down or adjust, and I pull my hammock as tight as it can get between the trees. I just had ZQ remove the velcro and sew up the bottom slit to make my hammock softer feeling under my legs. I have her Mod #2 so now I only top-load.
This is how I use the Garda Hitch:
1. Estimate distance between trees and get both ends of the stock suspension rope Garda Hitched into the ring buckles. Use a bight (sp) in the line for easier release later. FYI, I use SMC descending rings. Bought them online from someplace in Seattle. I have girth hitched two rings to the end of each tree-hugger, which I wrap around the tree and clip through a lightweight 'biner. Each tree has a tree-hugger, lightweight 'biner and two SMC descending rings.
2. Start tightening the hammock from one end, then walk across to the other end. Make sure its pretty centered, then tighten up, back and forth until you like the spacing between the trees. I make sure to fuss around as much as possible to satisfy my inner OCD gremlins!
3. Sit in the hammock as a lounger/chair to stretch the suspension some. Maybe 1 minute of sitting.
4. Tighten lines again.
5. If happy with suspension, confirm tightness, finish with a half-hitch and continue on to tarp and load gear. Sweet dreams! If not happy, adjust using this method . . .
6. To loosen the Garda Hitch, I pull the hammock with my right hand towards the tree. I grasp the hammock on the material between the zip-tie and where the rope goes into the end material. It's basically the material that covers the end whipping. This gives me enough "purchase" on the horizontal hammock suspension to create some slack in the suspension and takes some tension off the Garda Hitch. I can then grasp the end of the bight line with my left hand and more easily pull the bight through the rings and loosen the Garda Hitch. This is very difficult to do without taking tension off the rings. I don't always get the entire bight out through the rings with the pull, but by then I have so much slack that I can open the rings with my fingers and remove the rope.
7. Voila, Garda Hitch undone!
Good luck and welcome to HF!