1) Read ThisFor the love of God, read this before you do any interviews.
2) Be flexible with interview times...preferrably holding them out of hours. A consciencous interviewee who already has a job doesn't want to risk endangering that job, or waste their holiday allocation, or go through the minefield of taking time of work, if they can help it.
You will make it so much easier for potential recruits if you can do the interview out of hours, or in some way make it as easy as possible for them to get to the interview without disrupting their current job.
3) Test their development skills by getting them to develop somethingSoftware development is about developing software, not about knowing the definition of Dependency Injection or what the definition is of each of the method modifiers available in your chosen language. There is so much to know in Software Development the no single person can know everything, and by asking specific quiz questions, you're turning the interview into a lottery (for both you and the interviewee) where the "winner" is determined by who was lucky enough to have recently read the specific fact that you asked them.
Go through the process of developing software with them. Allow them to use Google and Stack Overflow, and discuss their code as they write it. Allow them to use technologies they are experienced in (or claim to be experienced in). In short, get them to carry out a microcosm of what the actual job would be.