Using Weasyl's Folder Options
Weasyl has the ability to customize how folders that you create inside your submissions gallery work! To do this, you must be logged in, and create at least one folder in Submission Folders.
Once you have done this, a new section will appear on your Submissions Folders page named Edit Folder Options. For example, here we've created the folder Really Neat Stuff.
You'll be able to select Really Neat Stuff as a link, and be taken to Weasyl's Folder Options. This is what it looks like:

Using Folders to Set Featured Submissions
After setting up a submissions folder, you can enable the featured submissions option on it. When you do, your options will look like this:

On Weasyl, if you do not have any folders enabled with this option, your profile page will prominently display the most recent image you've uploaded, with the header Most Recent.
When one or more folders has the above option checked, Weasyl will replace the Most Recent image on your profile with Featured Submission.
Weasyl chooses an image at random from among Featured Submission folders, to display as your featured submission, and does this with each visit to your profile page.
If you really want one single submission to always be shown as your featured submission, we recommend creating a folder with that submission inside it, and enabling only that folder with the Featured Submission option.
Creating a "Scraps" Folder
Many people like to have a folder where works created in it are not shown on their profile or submissions pages (or on Weasyl's front page), but do want their followers notified when they're uploaded. Typically Internet art sites call these "Scraps" folders. If you'd like your own, select a folder and set the following options, and you're done!

Avoiding "Spamming" Followers With Mass Uploads
If you plan to upload a lot of submissions, but don't want to "spam your followers with notifications", Weasyl lets you do this too! Create a folder, and set the following option on it:

You're ready to submit works into this folder, quietly! Once you're done, all you need to do is remove this option and followers will once again get notifications when you create new submissions in this folder.
Advanced: If you really want to be clever, you can go to Submission Folders once you're done with your "quiet" uploads, and delete the folder. This will move all of the submissions you've just "quietly" added directly into your "top" folder.