When you first start collecting minerals you should explore all types of minerals, all localities, all sizes, colors, forms, etc... Learn through your purchases - ownership brings knowledge.
As you gain expertise you will start to focus your collection. Some people collect only examples of one mineral, some collect only certain sizes, others collect single crystals with no matrix, some focus on a group of minerals (eg micas). Many collect for the beauty of the minerals - hence the term "House Jewelry". Traditionally many collectors have focused their collection on a geographic area - be it a single mine, a single district or even a single country. One of the popular areas to collect are the classic alpine locations of Switzerland. Here is an example of that location -
Orthoclase variety Adularia coated with Chlorite from Burg-Fiesch Glascier Area, Fiesch, Goms, Wallis, Switzerland.