The key thing for the smooth sketch effect is to create a good brush and I have found that a star design seems to be the best (for me anyway) so go to the polygon tool and quickly create a very basic star (set star radius in the settings to 50%) and apply in pixels mode and black. Once you have the star design, select the star and then go to the edit menu and define it.
Go to the brushes panel and select the art history tool, note that this may be displayed or not depending on your customization of the tools.
Go back to your original photo (say of a cat or a dog or person etc) and then blur it. Go to filter menu and blur and gaussian blur and set a decent sized radius for the blur. After you have applied the blur or perhaps an oil paint effect etc, go to the history panel (this can be found in the window menu) and then go to the left side of the entry that has the recent filter effect and click it to add a 'history state' and this is used as the source for the tool, without setting it, you would just be using the original image
You can now restore the original image or perhaps use a solid black color or white etc via the edit menu and fill for the start point for the effect
Set the size for the tool to about 9px or so. Set the blending to normal, opacity at 100% (or vary it if you wish) and set the style along the top to 'loose long'. Set the area to 50px
Hold down the mouse or pen and apply the stroke, you can move over the image and create more and more of the drawing. You can also apply more pressure to particular areas if you are using an art pad and pen to create more intense line work in certain parts of the image, The tool uses the lightness / darkness of the image. You can apply more in part of the image, you do not have to fill the entire image.
The colors that end up in the sketch depends on the original image, so if you want a black and white image then before you capture a history state for the smooth sketch effect, apply a black and white adjustment to the image or perhaps use a hue / saturation adjustment to make the image more green or red etc. You can also, if you wish, capture multiple color states for the image (before you do any sketching) and save them as a snapshot and then use the snapshots for the history state, resulting in kinds of wonderful combinations of imagery https://youtu.be/D7DAExuRbcg
You can also add different colors into the design by going to the settings panel and setting the color dynamics and setting a high hue / saturation etc value and instead of just the current image colors, you will see more random colors coming into the sketch.
If you wish, you can always add back the original image into the image by setting the history state to the original image and then going to the edit menu and fill and select history as the content and also using blending modes such as darken or lighten to layer more designs into the image (you could also just save the original image as a layer and work on a separate layer for all the brush strokes)
The strokes have all been added to the current layer, you can always add the smooth sketch strokes to new layers and build up multiple layers via the layer menu and new layer command. You can then use the layers panel to apply blending modes as well as add in bevel and depth and shadows etc via the layer menu and layer styles command to each of those layers.
You can continue to add more and more strokes in different parts of the image and layer your strokes to create a complex image or a very sparse one.