Owl
Spray down your tomato plants with a standard insecticidal soap, available from all garden stores and nurseries OR make your own by mixing a quart of water with 2 tbsps. of liquid dish soap. Insecticidal soaps are sufficient for light infestations, and are typically gentler than using chemical-based insecticides.
then,,
Mist a commercially prepared insecticide intended for garden use onto your affected tomato plants if you have a heavy leafminer infestation. For best results, use an insecticide made with abamectin or cyromazine, to which leafminers are susceptible. Spray evenly on all exposed tomato vegetation according to the label's guidelines, as toxicity varies widely by brand.
Then,
Apply a spinosad-based spray, many of which are organic. These type sprays are ideal for those who want something more powerful than an insecticidal soap but don't want to apply chemical insecticides. Spinosad is a type of bacterium that's toxic to tomato leafminers but won't harm beneficial insects like lady beetles.
I hope this helps