Check the print and weave
Look at how dark and wide the printed line is, then choose a thread that can cover it without requiring a very dense row. The cloth weave determines how much of the ink remains visible between stitches.
If the print is faint, a fine thread may be enough. If it is bold or coloured, a fuller thread or a slightly shorter stitch can help keep the guide hidden.
Use a small corner sample
Stitch a corner or spare area first, then view it at normal distance. A thread that looks opaque close up may leave marks visible across open sections or inside small corners.
Test the intended washing method as well. Some printed guides soften after washing, but do not assume every ink behaves the same way without checking the product information.
Keep the surface even
Pre-printed patterns are often chosen for learning, so a stable medium-weight thread makes the route easier to follow. Avoid changing strand thickness halfway through unless the design intentionally calls for it.
Let the thread lie on the surface rather than pulling hard to erase the print. Tension that is too tight can distort the cloth and make the printed line curve away from the intended path.