Keep in mind that any person's potential for success in a given job is a function of three factors. Don't be reluctant to ask candidates what they have done, and how well they did it. Ask about their successes and the problems they've faced. Ask for references and call them. Verify education and training as well.
Motivation is based on what an employee gets from performing the job.
And while salary is important to performance, it's not everything. The best employees are those who enjoy what they do. Your task in hir- ing is to find people who want and like to do the job for which you are hiring them. When interviewing, it is also important to know the laws related to job discrimination. If it isn't, don't ask.