Cuidados!

Use solo(a) as an adjective to mean alone. The kid went alone to the dance.

Use sólo as an adverb to mean only. There is only one brand of shampoo that I like.

Use realizar in the sense of to carry out or achieve. The girl achieved (carried out) her dream of becoming a designer.

Use darse cuenta de to mean to realize or recognize. I realized it was out of style.

dejar + direct object means (to leave something) I left my car in the parking lot

Dejar + infinitive means to allow or to let, my parents didn't let me drive at night.

Dejar de + infinitive + direct object means to stop doing something - did you stop looking for a new car?

Calidad and cualidad are both cognates of the English word quality, but have different meanings; calidad - quality, as in a measure of worth, cualidad - quality, as in a characteristic of a person or thing.