BTW, where does the Angel go if theres string there?
I tie the string down low (clove hitch, for those of you, me included, who are anal about knots and always must use the right one, for the job. but if thats you, then you probably already knew which knot to use

)
then a couple half hitches on the top just below the angel.
then the string runs up her dress and out through the collar.
this trick has saved the handmade angel that my wife made at least 5 different times. not only will the tree not fall over, but the string keeps the angel on top even if the tree takes a hard hit (like a 6 year old tackling a pitbull into your tree at a dead run)