Any other ideas?
Yep -- after you paint, put down stick-on stair tread tape. They have several brands for sale at Home Depot -- here's an example: hyStik 770 2 in. x 5 yds. Black Anti-Slip Tape (1-Roll)-770-2-Bk at The Home Depot
We put this down on slick stairs to help an oldster and it REALLY helped. The difference was like night and day -- bonus: it made it safer for humans too! It held up for 2 years for us. We're just now needing to replace it.
A pricier solution is to use decorative rubber stair tread mats, which have to be nailed in place. They have some pretty designs, but you are limited to a small selection of sizes, and you have to potentially buy a lot of them. Here's what they look like:
Entryways Fleur Di Lys Stair Tread 9 in. x 30 in. Recycled Rubber Door Mat-194R at The Home Depot
We put the deco mats at the top and bottom only, as they offer a texture change for the blind dog. The middle all use the non-slip tape.
It rains A LOT where we live, and the porch stairs have an oil-based paint on them that is very slick when wet. The tape solved the problem.
ETA: you can get the paint grit stuff to mix into regular paint. My handyman did that when he painted a dog ramp he built me for a geriatic dog. The grit additive in paint does help. I'm not sure I'd rely on it alone.