When looking for your builder, make sure you are not just dealing with a marketing company and they are real builders. Currently in Melbourne and around the country there are many marketing companies masquerading as builders. This is a major problem the industry has at the moment and the practice should be banned. 

Ask to meet the builder before you sign anything and definitely before you part with any money. If meeting the builder is a problem at the start, imagine how it would be if you start building with them. Remember you are spending a lot of your money, possibly the largest investment you will ever make and you need to be able to trust your builder.