I've placed a soft focus filter by Cokin in front of my enlarger lens just recently. To my surprise, the results were quite nice. It's different from out-of-focus images though.

Placing a tracing paper/tissue_paper right on top of printing paper didn't do all that much.

My next step will be to place a plate of glass a bit above my paper and apply some Vaseline on it.

I had a print that had distracting elements. I was able to bring attention away from them by burning in that area. Eyes naturally go to brighter areas and areas where there are abrupt contrast changes. You could try that, too.