You need to run cron frequently (for example, every 10 minutes). And meet some problems on this way.
Modules launched by cron work with external sites and connection with them can be bad or script …

 
This article would tell you how to create back of database automatically on a regular basis.
Solution (for Unix users):

This article would tell you how to create backup of your Drupal-based site in different ways:

Using Unix command (you will need SSH-access for this)
Through site control panel
Downloading files by FTP from server

Using Unix …

This article would tell you how to manage your Drupal-based site on Unix-server through terminal (SSH).
Solution

 
This article tells how to speed-up CSS and JS files uploading by means of compression on server and passing compressed copy to browser.
Solutions

Automated compression by server
Create archive for every JS/CSS file and …

This article would tell you how to set cron launching.

For the correct functioning, some modules require regular technical maintenance. For example, watchdog module needs to remove old messages and search module needs to index site content.

Solution
Idexing
Decrease number of documents for indexing at one cron launching on the page of search settings. It’s better to run cron a few times a day.
Mailing
If you have simple news then it can …

So you should create subdomain for every user. For example,

http://mary.example.com 
http://kate.example.com 
http://jeff.example.com

This article is about storing information about site development. You will be able easy find it and make your corrections. Besides, sometimes you should pass this info to other web-developer.