Concrete can be very slippery when wet, especially if the surface of the concrete is smooth troweled, polished, or dense. There are a few different things that can be done to help make the concrete more slip resistant:
You can apply slip resistant pads or grip tape to various areas of the concrete to help provide more slip resistance. Slip
resistant tape is cost effective and easy to apply.
You can apply slip resistant mats to high traffic areas to provide more slip resistance. Mats are available in all types of shapes and sizes online.
You can acid etch or diamond grind the surface of the concrete to transfor smooth concrete into rough concrete. The level of roughness achieved can be controled with level type of grinding method used.
You can apply a concrete coating and add a non-slip additive to the surface. The non-slip additive is a fine to coarse granular additive that gets added into the top coat. 3-4 ounces per gallon can be added to help achive a more slip resistant surface.
Penetrating concrete sealers will not make the concrete more slippery, but they won't change the slip resistance of the surface because they work entirely below the surface from within the pores. Concrete densifiers and water repellents sealers are great sealers for protecting the concrete without changing the look or color, but they can't add more surface traction. An acrylic sealer or concrete coatings are the only types of products that can be applied to concrete to make it more slip resistant, simply because the non-slip additive can be added directly into the top coat.