Here are some really easy and good to know recourses so you don't have to search many stuff yourself.
After you create a new Project you need to setup the Spigot API. To do that you need to head to File -> Project Structure (or alternatively you can hit CTRL+ALT+SHIFT+S). After that navigate to Libraries, hit the + and select the Spigot.jar with the appropriate version. You should be able now to use the API for your plugin.
Building Your Project
Building your project has a few small steps. After completing them your should be able to build your project at the location you want with the name you want. First off, head to File -> Project Structure (or alternatively you can hit CTRL+ALT+SHIFT+S). After that navigate to Artifacts, hit the + and select JAR -> From modules with dependencies... -> OK. After that delete the Extracted 'spigot-x.jar'. You can also specify the output directory and the extracted .jar's name. Now you should be able to build your project by going to Build -> Build Artifacts, this will extract the .jar file in the output directory you set. And you are good to go!
Here are some really good and helpful plugin recommendations that can help you through out your coding. You can install plugins by going to File -> Settings -> Plugins (or alternatively you can hit CTRL+ALT+S).
This plugin does exactly what the title says and it's really configurable. An example of how it will look in action is the following.
This is a really useful plugin as it makes your brackets colorful. This is really useful when you are dealing with a lot of brackets and parenthesis. Example is the following.
One Dark Theme
This is just a simple theme. Personally I find it really great. It's not very dark but not light either. It's really good on the eyes and really helps colorblind people like me. Here's how it looks.