Several parameters must be taken into account to fish well with a spinning rod. The main ones are the size and weight, the shape of the paddle or the color of the paddle.
The size
There are many sizes of spoons for trout stalking. Most of them range from size 00 to 3 for the stirrup models and from 1 to 4 for the in-line models.
In small streams, on shallow sections, small models are naturally preferred. In addition to their size, they are lighter and therefore more suitable for fishing shallow areas. At the head of the pond, in fast flowing areas, use models N°00 to N°1 and N°1 to 2 in-line
In rivers of plain or on the bottom of torrents, we can increase the size by using mainly spoons N°2 to 3 and 2 to 4 in-line.
It will be necessary to regularly adapt to the size of the fish or to the strength of the current. In any case, you should not hesitate to change sizes. The N° 1 and 2 are really all-purpose, but you would be surprised of the results by switching to the N° 3 or N°0 which can make the difference in certain conditions.

Sometimes it's the big vibrations and the strong incentive that triggers the keys, sometimes it's the opposite with less present and more natural stimuli.
The choice of the model
I prefer the use of nail palettes to fish upstream, especially in small streams. The in-line paddles are also relevant even if they are less present. In small streams, this is well noticed by the salmonids posted.
I also use the nail paddles in competition, especially on the first rounds, when it is necessary to catch active fish that have not yet been caught with an ultra incentive lure.
I use in-line patterns when I want to fish deep and slow, whether it's in streams or flatwater, upstream or downstream.

Finally, I favor willow leaf paddle patterns in powerful rapids to cross a current or fish downstream.
The choice of the color
Silver is a timeless and effective base almost everywhere. The black, contrary to popular belief, is my second choice. Every year I catch a lot of trout with black paddles on mountain streams as well as on plain rivers. This is paradoxically more natural, the spoon does not vaguely imitate a fish, but more an insect, a tadpole or an invertebrate evolving in the water.
The walleye or copper are very fishable in acidic rivers or when the water is clear and the light is strong.
Finally, fluorescent colors, yellow, orange or pink are very relevant at the beginning of the season or in prickly waters.