How to increase percent of successfully registered users ?
The thing is that Joomla 3.x by default have 6 fields on registration form what is not always good for marketing purposes.
Even new Joomla 4 (which is now available as alpha) won't change this situation significantly - it still has 5 fields.
If you look at registration form of the biggest and successful companies like Amazon or eBay you won't find there big registration forms.
They know that each field decreases chance of successful registration by 10%, that is why they prefer to keep it simple.
Another issue with Joomla is that it still requires username (or login) which is actually thing of the past and in most platforms were already replaced by email.
Username is not just another field, it is real problem in marketing world. Username requires extra efforts from client - which username to select, what to do if selected username is already taken and so on...
Only username field was the reason of 17% of unsuccessful registrations on our website, so we get rid of it 3 years ago too.
The main goal of registration form is to collect basic information about user which is already a barrier from successful sale and there is no reasons to make this barrier even higher.
So, the main rule is to ask as much information from user as you need for current functionality of your website - if you need extra information about user for further work - ask this info later (after registration).
Solution for Joomla:
Our goal was to allow our clients to remove any fields from Joomla registration form, so the simplest registration form should have only 2 fields: Email and Password.
As these fields were part of Joomla, the only way to simplify registration form was to create special tricky extension for it.
After days of research and digging into Joomla source code we managed to find solution which will work perfectly on Joomla 1.6, 1.7, 2.5 and 3.x.
Results of our work you can find here: Simplify Registration Form, Remove Fields