My first attempt at grafting was unsuccessful (and amateur). Having purchased some grafting tape, I re-did the initial orange bougainvillea grafts using grafting tape, and a specific grafting technique, whip and tongue, which you can see from the photographs provided (these are two grafts on the same specimen).

The grafting tape is supposed to prevent diseases infecting the rootstock, and allow the absorption of moisture, while holding the scion in place. I also added rooting hormone to increase the chances of the graft taking.