I give away a different Serum preset that I have created every week. To see what free downloads are currently available, you can find this on the Giveaways page.
This post is a step-by-step guide on how to add new Serum presets.
1 | Find the folder where your existing Serum presets are contained
By default, on Windows – this location is:
C:\Users\<username>\Documents\Xfer\Serum Presets\Presets
If your Serum presets are stored elsewhere, you can find the directory path by loading Serum and clicking the floppy disk icon to bring up a save dialog box. The directory path for User presets will be in the navigation bar, you can copy this and paste it into File Explorer.

Once you have reached your Serum presets folder, you can create new folders and sub-folders to organise your presets.
2 | Move the preset into the correct folder
It may help you to keep track of your downloaded presets by creating a folder inside the Serum presets directory called “Downloaded Presets” and then having sub-folders for each site you download from.

Once you have created the folders you want, move each preset (.fxp file) you have downloaded into the appropriate folder.
3 | Refresh all plugin instances
In order for the changes you have made to be reflected in the UI, you need to close and re-open all plugin instances. Make sure you have saved your work before you do this!

Once this has been done, you should be able to access your presets within the Serum UI.