One of the best things about using WordPress is the plugins. Thousands of developers create plugins and a lot of them are free. I have been adding plugins to a new site today:
1. WordPress SEO by Yoast
I use the Genesis Framework for all my sites which comes with a lot of SEO functionality. This plugin comes with additional functionality and instructions how to optimise your site.
By default the plugin gives your site great SEO. The options I have changed on other sites are titles and meta descriptions for the homepage and ‘blog’ page (for increased clickthroughs).
2. WP Security Scan
This plugin makes your site more secure. Hackers are constantly scanning the net for vulnerable sites. If you install this plugin and follow the instructions you can vastly increase the security of your site. Making your site editable from 1 IP address and securing the wp-admin page are a couple of the security steps.
3. BackupWordpress
If you value the content on your site you need to back it up. If files become corrupted during an update or if the whole site gets deleted, you have a copy of the site and can get back up and running. BackupWordpress is easy to use and can be set to automatically send backups to an email address.
4. Digg Digg
This is a social sharing plugin, used by a lot of popular sites eg. Mashable. You can make it easy to share your web pages through 24 social networks with Digg Digg, though you might want to make this number more manageable 
.
5. Fast Secure Contact Form
If you want people to be able to contact you through your WordPress site the best way is through a contact form. Using a form you don’t have to put your email address on the site, which can be picked up by bots for spamming. It looks professional and you can customise the form to request the info you need.
6. All In One Favicon
The favicon is the tiny image that appears next to the page title in the web browser. You can customise it with this plugin which accepts png and gif files as well as ico files.
Further Recommendations
Premise for WordPress
On some pages the action you want visitors to take should be very specific. Landing pages are pages on your site dedicated to converting visitors. That might be to leave their name and email address or to buy something.
To create landing pages properly you need a plugin. Premise works with any WordPress site to create fully customisable landing pages. Premise is a premium plugin. When you buy Premise as well as the plugin you also get access to a knowledge base which teaches you about landing pages and copywriting. The knowledge base is excellent and teaches everything from PPC optimisation to increasing traffic and conversion optimisation.
Mailchimp and Simple Popup
If you want an easy way to increase signups to a mailing list use the Mailchimp widget with Simple Popup. When visitors land on your site a popup appears requesting name and email address. You can set the time delay and other options and its a free solution.
Hope this helps,
Joe
WordPress Plugin Recommendations For a New Site is a post from: Think Genial: Social Media Management