Take a look at these facial expressions and try them in your own drawings.
To make your anime character look like they are in love, replace the eyes with two rounded hearts. Remember to add highlight to the corners to create a better effect.
A happy expression in anime uses two thick curved lines for the eyes and a wide mouth to create a happy, laughing face.
An annoyed facial expression can be made by pointing the eyebrows down towards the centre. The eyes use a thick line with a semicircle underneath. The mouth is slightly curved.