Hi Starr, begin by selecting ones which appeal to you in the first instance. I'd recommend a nice piece of clear quartz for anyone beginning a collection and their uses are many and varied, they can be used for healing, boosting self confidence, enhancing or assisting with the development of any spiritual gifts you have to name but a few uses.
They can be 'programmed' or 'charged' for specific uses, and i'd also recommend a good book about crystals which will explain further their individual properties and advise you on things such as cleansing, (usually water does suffice but it can damage some crystals.) A good book is The Crystal Bible for learning the basics though you can also buy books on crystal healing too.
A good shop will allow you to 'handle' crystals when you are buying, usually the one for you will 'feel right' as soon as you pick it up or you may keep returning time and time again to a specific one, this is the crystal 'drawing' you.
Do keep us updated on your collection :flower: