I have some plugins for WordPress that when I go to create a new site, I tend to install them because I have found them useful and they are mostly free. I will now tell you about them here.
WP-Spamshield Antispam is the very first one I usually install. It’s completely free (though the authors accept donations) and it works against every type of spam out there – including registration spam – and there are no captchas (or other such problems) to worry your visitors! It has kept me spam-free for quite a long time!
No Page Comments is another plugin that is almost always installed by me. It stops comments, trackbacks, and pingbacks on the pages (and custom post types) of your website, so if your pages are for displaying member profiles and other info in a community website, this stops the comments from even being entered!
I always install Jetpack (by WordPress.com) to track how well my sites are doing, besides all of the other useful things it can do. It adds a mobile theme easily to my sites, adds useful widgets and can control who sees them and when they see them, and has sharing built-in, saving me from adding a sharing plugin.
If I am creating a membership site of any kind, I always install Ultimate Member these days. It’s more flexible than BuddyPress (not every membership site needs a social wall), and integrates (if you buy the add-on plugins or extension pack) with WooCommerce and bbPress smoothly.
WooCommerce is my e-commerce plugin of choice, because like I said before, it integrates with Ultimate Member (via a plugin) and also with myCRED (also via a plugin). It also has all the payment gateways I could want (even if I have to pay for some of them via paid plugins), and is relatively easy to setup. It also integrates perfectly with my theme of choice, Headway.
Code Snippets is my recommendation if you need to add some code to add a function to your website, but don’t want to risk losing your changes via an upgrade. It also makes disabling them a breeze if you screw up, or don’t need the code working on your site anymore.
Finally, myCRED is my credits plugin of choice for WordPress. It works seemlessly with any theme, and is the perfect choice for rewarding members of any site. It integrates with lots of plugins (some via paid plugins) and the author provides support via the forums on the plugin’s website.