How Can I Make A Story More Interesting If I'm Stumped?

Best time to add a unexpected event could route your story in a different  way twists and turns make the greatest stories of all

Put suspenseful things in your story. (Such as being attacked by aliens!)

That's not much to go on! What kind of story is it? Fiction, Non-fiction, Reference? If it's fiction, try adding some characters that are fantasy characters for yourself. What do you want to be. What did you what to do but haven't had a chance to do. Things like that. Be more descriptive of the characters. Working a little on character development will open up a thousand doors and possible plot lines. There are a million things to try in fiction because everyone expects to be wowed but fiction. The sky's the limit! Go for it!  Don't try to wow everyone all the time. Just please yourself at first.If it's non fiction you must use facts. One way to be more interesting is to be more descriptive and use more details if you have them. You can do some research for those details. For example if you are writing about a bus, what kind of bus, how many people does it carry. What color is it. Get some details from other sources like the manufacturer or a bus expert like a mechanic or the engineer who designed it.If you go that far then you have entered the realm of Reference. And you might as well write a repair manual for that bus.I hope this helps.

Exhilarate your story everytime you write.....always read books and practice writing....