I love making custom Dresses. It makes the design process easy, you just ask the customer what they want. Since I made a goal for myself to make dresses even if I don't have customers in order to start a design line, the design process is different.
I have to guess what people would like. As I have mentioned before there are companies that forecast trends, color trends, shape trends, silhouette trends. Most designers take a look at this type of forecasting and then just have it in the back of there minds while they are designing.
Again I don't have money to spend on a forecasting package, so I take what is free. FirstView.com is a website that photographs designer shows and puts the images online, the current lines are pay-per-view, but there are old design lines that are Free. I like to go there and see what Designers have put out in the past and try and forecast what they might be doing in the future. Here is a link to a search result for Free Bridal collections. Hope you enjoy it as much as I did.