Be sure to make peace with the concept of friendship first. For example, what your expectations are. Keep those in mind when you do the working.
I say this because the cultural value of friendship has deteriorated a lot across the centuries, especially in the last couple of decades with Millennials, their parents and all the generations after them. The concept of friendship on the spiritual level remains intact. Just like family, friendship culture will need to undergo a purification process to bring it back to the source from this current superficial, decadent level.
Also, remember that friendship doesn't happen immediately but takes time to build like any relationship (and literally anything) worth its salt. The first stages are of acquaintanceships, which many younglings today vainly and incorrectly refer to as friendship.
A few runes can build a bridge between two people. Just read their basic descriptions on JoS, and you'll find what you need. In Sanskrit, you can use Mitra/Maitra (friend) or Maitraka (friendship). Personally, however, I prefer using runes or Parisakhya (perfect/true friendship). In descending order, Aquarius, Libra, Sagittarius, Leo (only friendship with males) and Taurus are the best Moon signs to do this. The rest has already been explained by Henu.