I think that Rakhi should be observed as a solemn festival to reaffirm the warmth and affection shared between brothers and sisters but now it goes way beyond this to become a boisterous and pompous celebration. Rakhi tying is meant to strengthen the oneness and togetherness of the family by rejuvenating the emotional bond of love and affection between brothers and sisters.
The observance of the festival should begins in front of a lighted lamp which signifies fire deity, followed by a prayer, red Tilak ceremony and the sister tying the Rakhi as red thread on her brother's wrist and the brother pledging to protect her under all circumstances. In fact, colour red signifies fires, one of the five elements that support life according to ancient Vedic philosophy. The prominence of red on Rakhi signifies the fire element representing warm relationship, security and protection.
Here is my acrostic on RAKHI as message.
R: Relationship and emotional bond of
A: Affection between brother and sister by
K: Knotting a sacred red thread around the wrist of the brother by the sister for
H: Harmonious social life and sacred
I: Intention or promise of protection of the sister by the brother