Have you made a jam and just got 3 entries when it ended? Well, I have a tip for you. This is only based on my experiences on making a jam, because:

I made Festival of Frost with 100 submitted entries and 162 members joined, The Illagers and Villagers Jam with 64 entries submitted and 123 members joined, and my Early Days Jam that currently got 98 members joined and 23 entries submitted (expected to get higher joins and entries)

Why? How I made such a very successful jam?

Here's what I did:

Make a Good Name for your Jam

Your jam names must be catchy. Your jam names must be short so everyone can understand it (ex. in Festival of Frost, it clearly said that the jam is winter themed)

Create a Catchy Banner

Your jam banner must be simple, but it has the theme of your jam. This way, you can make your jam attractive to everyone.

Hire your Judges

Don't just hire your judges simply. Your judges must have the knowledge of creating a jam too. Hiring your judges means "Teamwork makes the dream work".

Just like other jams, like Nether Empire, made their own sequels. You can do the same, so if your jam isn't good, you can make a good sequel of your original jam. Just remember, this is just my experiences on how I made a popular jams.