Many factors:

Apply them only when necessary

Use fast degradation ones

Take into account the weather conditions

Avoid drift

Avoid applying near sensitive areas (wild life, water bodies, bees, etc....)

Apply the recommended minimum dosage. And select narrow-spectrum herbicide. Also, find out if it is safe for the soil and non-target organisms.

what about use anotherways?

Use novel herbicides and integrate herbicides with natural enemies to control pests in agroecosystem.

One of the most important aspects that has to be kept in mind is to apply herbicides precisely following principles of precision agriculture 4R' viz. Right amount, right time, right method and right place or space which is based on managing variability in time and space... recommended optimum dose has to be applied...Select herbicides which are of less persistence periods that is non residual or less residual herbicides...Method of application may also play important role to apply herbicides more effectively to enhance efficiency, recovery while maintaining sustainability...Another important aspects is non chemical weed management and integrated weed management where by one can integrate any of the weed management practices with herbicidal strategies so as to substitute the considerable percent of herbicides doses and rate of application....