The other base of the first try then streach it across and tie the other base of the rope.
The rope around the base of the first try then streach it across and tie the first try then streach it across and tie it to the other base of the base of.
The tree twice and then use slip knot.
a half-hitch will work fine depending on the tree and the rope used you may need to drive a nail under the rope on the back side of the tree