Most popular modules

Generally speaking, to install a module, uncompress it and copy to the modules folder, usually: sites/all/modules/,
then go to: Home > Administer > Site building > Modules to configure them

If you don't see nothing in the modules list the modules may need permission and the cache should be cleared in :
Home > Administer > Site configuration.

Some modules will require you change permissions to get them working. Permissions information may be in the instructions that came with the module.

Usually, go to Administer > User management > Permissions

1. CCK (Content Construction Kit)

CCK is a contributed module that allows you to:

1. Add fields to an existing Drupal content type
2. Create new custom content types

2. Views

The Views module provides a flexible method for Drupal site designers to control how lists and tables of content (nodes in Views 1, almost anything in Views 2) are presented. Traditionally, Drupal has hard-coded most of this, particularly in how taxonomy and tracker lists are formatted.

3. Pathauto

The Pathauto module automatically generates path aliases for various kinds of content (nodes, categories, users) without requiring the user to manually specify the path alias. This allows you to get aliases like /category/my-node-title.html instead of /node/123. The aliases are based upon a "pattern" system which the administrator can control.

You should enable Clear URLs.

4. Administration Menu

The module renders all administrative menu items below 'administer' in a clean, attractive and purely CSS-based menu at the top of your website.

5. Google Analytics

Adds the Google Analytics web statistics tracking system to your website.

6. Nodewords

This project allows you to set some meta tags for each Drupal page.

7. Global Redirect

Avoids duplicated contents through url, all the urls like: /node/1234
will be redirected to the users friendly path aliases generated by Pathauto

8. XmlSitemap

The XML sitemap module creates a sitemap that conforms to the sitemaps.org specification.

9. Page title

Controls the page title where you can manually write the value of the <title>Page title</title> tag.

10. Wysiwyg

Use Wysiwyg editors, to install Fckeditor, TinyMCE and others

11. ImageField

To associate a field to an image and make it link to the node content.

12. Search

The search module doesn't need to be installed as it is part of Drupal core, but to be seen by everyone you need to configure permissions, so go to:
Stie Configuration > By Module > Search > Configure Permissions

Open the Permissions Form and check all of the anonymous user's permissions.
That's it.

13 . Token

Token module provides a centralized API for text substitution. Install it mostly because other modules (like Pathauto needs it)

14. FileField

A widget to upload files

15. TinyMCE, Fckeditor

This are known WYSIWYG editor that worked for a Drupal 6 instalation.

16. cleanURL

This option makes Drupal emit "clean" URLs (i.e. without ?q= in the URL).

DEPENDECY

Check on Home > Administer > Site building > Modules

To see if all missing modules are installed, some modulse depend on others to work, like FileField and ImageField.