There are many ways you can separate mixtures without using a strainer or handpicking technique. Choosing the correct method of separation depends on the nature of the mixture you're trying to separate.
1) Decantation separates immiscible liquids based on different densities.
2) Chromatography can also be used to separate different types of mixtures. However, this method requires laboratory expertise and equipment.
3) Distillation separates liquids by exploiting differences in boiling points (i.e. selective boiling and condensation).