If the cutting is fresh, a rooting hormone is hardly necessary. Older or less fresh cuttings will benefit, as will difficult to root cuttings like the Singapores. What is MOST important is warmth! Supply consistent bottom heat, and mist the cuttings occasionally until you see growth. As far as gel vs. powder, it doesn't matter. The concentration of iba is the same. Products like Dip-N-Grow allow you to customize the strength for difficult to root cuttings.

Also, cuttings taken in spring are often easier than those taken in fall.