Hi,
As you are already a End User of SAP you should be well aware of the purchasing and Inventory Management process to be a MM consultant. Initially try to practice all the business scenarios and complete the process cycles which are implemented in your organisation. After which try to figure out the prerequisites (eg,Vendor,Material master etc) which you are using in the cycle try to prepare the same.Post which start exploring the config settings made for these cycle to work. Gradually start exploring other module related settings made. Eventually you will be a consultant on your own.