This one for example, un-processed still is a 40sec exposure@ISO3200, you can see the trailing beginning.
Sometimes it takes a few shots to get a good one. You also need to consider if it's other movement causing the 'star trails'.
The actual tracking increments of the scope can cause trailing of the stars too sometimes. Some nights you can even see it through the eyepiece the object jitting as the motors step to track the object.
And you also want to remove anything from the camera that will cause vibration like the neck strap blowing in the breeze. Don't use your finger to start the exposure on the camera, rather use the inbuilt timer or do it via cable/IR remote. Consider using the mirror lock up function on your camera.
And depending on the position in the sky also will determine how long the exposure will be before it starts trailing (well at least that's what I've found, I haven't got a theory why yet). Some can only take 10-15sec max others up to 30-40sec like the image above.
I found my exposures needed to be shorter as I approached the south celestial pole, and I could increase them further away. The Orion photo above was taken pointing near on straight up, and it handled a lot longer than I expected. Whereas when I tried to capture the Tarantula I was flat out getting 10sec before stars dragged.
