I have found it impossibly difficult to achieve success with grafting.
Tried a large fig tree - absolutely prolific but so tasteless even birds and rats don't eat it. Tried to graft a sweet fig onto it. Of about 40 grafts over time only 5 survived and each has grown to about the size of my hand in total leaf surface area. I am now in the sixth year of attempts and only one has figs on it (six figs to be exact).
Tried whip-and-tongue, cleft, chip etc etc. Followed all the advice at the head of this thread (approximately). Only about 10-15 scions took but then would rot off or would fall off or would dislodge when I remove the tape or would break off later (maybe birds?).
Sigh.
So I have given up - I will leave the 6 figs to the birds (not worth going to all the effort to construct a netted cover for that) and go back to watching sport or drying paint.
Clive
Johannesburg
South Africa