It is very difficult to book a ticket in irctc.co.in during Tatkal time. Most of the time is spent to fill the forms(Plan My Travel, Passenger Details, Creditcard Details). Using the below forms you can create autofill for irctc.co.in.
For Help ??? Click Here. To See Video How to.
Note: Use Firefox Browser.

• Open this webpage before tatkal time.
• Click "Plan My Travel". Fill all the journey details and click on Create AutoFill.
  After this you will see a button Plan My Travel(DragMe to Toolbar) . Drag this to your browser tool bar as shown in video.
  
• Click "Passenger Details". Fill all the passenger details and click on Create AutoFill.
  After this you will see a button Passenger Details(DragMe to Toolbar). Drag this to your browser tool bar as shown in video.
  
• Login irctc.co.in and Click on Plan My Travel button which is in browser toolbar.
• Select your train and click on "Book Now"
• Click on Passenger Details button which is in browser toolbar
• Enter the captcha and make payment. That's all.