I have owned a retail clothing store and am in the process of opening a new one. My advice is to start with the business plan. Look through the SBA's website for general guidelines. Or look here for a step-by-step manual that walks you through the process:
http://www.smallbusinessstartup.biz/plan/

Typical start up costs for a retail venture are these:

security deposit
rent
utilities
signage
advertising
permits
legal fees
accounting fees
insurance
payroll
inventory
supplies
bank fees
loan payments
equipment
pos system
racking
counters
credit merchant acct
office furniture
office machines
taxes, taxes, taxes!

To obtain wholesale info do internet searches on the products you want to carry and go to their web sites. They offer wholesaling info right there. They will require your reseller ID #. Wholesale prices are typically 50% of retail and they require that you buy in lots. Obtaining inventory is very costly. Unless you are independantly wealthy, you will likely need financing. To obtain funding you will need to have from 20 - 30% of the total requirement yourself. You need to come to the table with your own money in order to get a loan.

In addition to the the cash requirement, lenders will also want to see that you have experience in the industry.

For those that are able to afford a franchise, that is a great way for the beginner to jump in. A good franchisor will have most of the start up processes in place including vendors, advertising, site selection, training and ongoing support.

My One Stop Business Startup Kit (see below) contains all the information you need to get you started.