What do you want
First of all, you should determine the type of keynote speaker you need. It is not possible without knowing the mental calibre of your audience. There are many types of keynote speakers for example, some engage the audience in humorous way, few go for philosophical talk and some just like to have a general approach. It is completely your decision as to what kind of flavour you want to offer your guests.
Do some research
Next thing is to do some research and make a list of professional keynote speakers. If you have attended a couple of writer's conferences then it won’t be difficult for you to compile a list. You may contact the organisers of those sessions and request them to provide you the contact information of some professionals. You can also browse the internet as most of the professional keynote speakers have their official websites/blogs or fan pages.
Determine your budget
You must know that a keynote speaker will not show up for free so it is better to know your budget first. In this way, you will be able to narrow down the search and ultimately you will be able to hire the right person for the job.
Now, when you have decided everything g about your guests, budget and the nature of keynote speech, it is time to shortlist a few names. You should call them individually and evaluate their skills. You can also ask them to invite you in any of their sessions as it will be easy for you decide after watching the audience’s reaction to their speech.
Make an offer
You should not give an impression that you have decided to hire the person. It is always better to bargain so just make an offer below the advertised price and then find some middle ground.