What a great question. It can be scary trying to buy a property without actually being present. Having a licensed Realtor will help put your mind at ease.
First thing to do is go get prequalified for a loan, so that you know how much you can spend.
Second, make a list of areas you would consider buying in.
Third, determine what are the property must haves? 3 bedrooms, 2 bathrooms etc.
Finally give your Realtor all the information you can about what you are looking for and how soon you hope to be able to buy.
In all reality, you will likely still want to come out to Hawaii and look over any property, condo, or home you are going to buy. Before you buy it.