1. The construction a + pronoun (a mí, a ti, a él, etc.) or a + noun is optional most of the time. It is used for clarification or emphasis. Clarification of le gusta and les gusta is especially important since the indirect object pronouns le and les can refer to different people (him, her, you, them, you all).

2. Use the plural form gustan when what is liked (the subject of the sentence) is plural.

3. To express the idea that one likes to do something, gustar is followed by an infinitive. In that case you always use the singular gusta, even when you use more than one infinitive in the sentence.

Example of #1

Clarifications and emphasis when using gusta

Using a + pronoun or a + noun is usually optional, but for gustar it is important since the indirect object pronouns le or les can refer to different people.

Examples:

A él le gusta llevar ropa cómoda. (clarification)

He likes to wear comfortable clothes.

A Ana le gusta esos pantalones de lunares. (clarification)

Ana likes to wear comfortable clothes.

Me gustan esos pantalones de lunares.

I like those pants with the polka dots.

A mí me gustan más ésos de rayas (emphasis).

I like those striped ones even more.

Example of #2

I like the suit vs. I like the suits

Me gusta el traje

I like the suit.

↓

Me gustan los trajes.

I like the suits.

Example of #3

Expressing when one likes to do something.

When gustar is followed by an infinitive, you always use the singular gusta, even when you use more than one infinitive in the sentence.

Examples:

Me gusta ir de compras por la mañana.

I like to go shopping in the morning.

A Pepe le gusta leer revistas de moda y llevar ropa atrevida.

Pepe likes to read fashion magazines and wear daring clothing.

Nos gusta hacer ejercicio y andar antes de ir a clase.

We like to exercise and walk before going to class.

encantar: to love; delight

Me encanta ir de compras.

I love to go shopping. (Shopping delights me.)

fascinar: to fascinate

A Doug y a David les fascina la tienda de ropa Rugby.

The Rudgy clothing store fascinates (is fascinating to) Doug and David.

hacer falta: to need; to be lacking

¿Te hace falta dinero para comprar el vestido?

Do you need (are you lacking) money to buy the dress?

importar: to matter; to be important

A Juan le importa el precio de la ropa, no la moda.

The price of clothing, not the style, matters (is important) to Juan.

molestar: to bother

Nos molestan las personasa que llevan sandalias en invierno.

People who wear sandals in the winter bother us.