The WordPress plugin ecosystem is one of the platform's greatest strengths and its greatest liability. Almost any functionality you need exists as a plugin. The problem is that not all plugins are created equal, and a bad plugin choice can slow your site, introduce security vulnerabilities, or create a dependency nightmare.
What to Look For
Active installations and update frequency. A plugin with 500,000+ active installations that was last updated 3 years ago is a red flag. A small plugin that's actively maintained and compatible with the current WordPress version is often a better choice than a popular one that isn't.
Code quality. This requires looking at the plugin's code, which most site owners can't easily do. As a proxy: check the plugin's support forum. How does the developer respond to issues? Are bugs addressed? Does the developer understand WordPress development conventions?
The scope of what it does. Plugins that try to do everything are almost always bloated. A plugin that does one thing well, loads only on the pages where it's needed, and has clean, efficient code is almost always preferable to an all-in-one solution.
What to Avoid
Abandoned plugins. No updates for 12+ months with unresolved security reports is a hard no.
Plugins that load on every page regardless of context. A slider plugin that enqueues scripts and styles on your contact page is wasting resources.
Duplicate functionality. Multiple plugins handling overlapping concerns (two SEO plugins, two caching solutions) create conflicts and confusion.
Free versions of commercial plugins from unofficial sources. Nulled plugins are one of the most common vectors for malware on WordPress sites.
The Right Question
The right question before installing a plugin isn't "does it do what I need?" — it's "is this the right way to solve this problem, or should it be built as custom functionality?"
For anything business-critical or anything that will be needed long-term, custom code is often the better investment. It's leaner, more maintainable, and you own it.