The most important thing is to be sincere and honest. You cannot bluff your way through estate planning and tax law. That means that you must make learning the technical aspects a regular part of your working day, like homework. Continuing education is essential. Study IRS and Tax Court rulings affecting charitable giving, read in the professional literature, and review relevant new tax laws until you understand them clearly.
Enthusiasm is very high on the list of what attracts gifts.
Sales ability is important, too, but not in the traditional sense. It must be based on a sincere desire to be of service. Finally, I think that it takes a certain kind of person to deal with the public, because the public can give you a lot of grief. Accomplished fund raisers are able to rise above that. That was true in my case.