Creating a new "Member" in one step
It should never be a 4 step process as the contribution and membership records are created at the same time. When you sign someone up for a membership offline via Add Membership on the membership tab of their contact record you tick the "Record Membership Payment" box and enter the payment during the membership creation or, if it is a credit card payment you choose Submit Credit card membership and the details for recording the payment are visible from the beginning.

You can get it down to 2 steps if it is a credit card payment and you make use of the "not you or want to do this for another person" feature at the top of the online sign up page.(The only step to do separately would be creating the onnected Joomla user.)

If you were using Drupal and the payment was by Credit card you could do it in one step if you used CiviRules to tag the contact when it was created and then implemented the steps outlined in Creating Drupal users made easy .

However, I note that you are using Joomla.  I don't use Joomla and don't know if anyone has created a similar method for creating Joomla users by tagging civicrm contacts.