para agregar una idea

Use the following transition words when you want to add a new idea to what you were just saying.

además – moreover, additionally

Estudiar español es muy interesante y, además, te abre muchas puertas. 
Learning Spanish is very interesting and, additionally, it opens a lot of doors. 

aparte – besides, apart from

Eso no es cierto, aparte de que ni siquiera es lo que yo dije.
That’s not true, besides that’s not even what I said.

asimismo – also, likewise

Asimismo is a perfect way to start a new paragraph building up on what you just said on the previous one. You can also use de igual manera or de la misma manera, to express the same idea.

Asimismo, las ideas de la Ilustración condujeron a la Revolución Industrial. 
Likewise, the ideas of the Enlightenment sparked the Industrial Revolution. 

también – also, too

Me gusta el fútbol y también el básquetbol. 
I like football and basketball too. 

más aún – moreover

No debiste mentirme, más aún cuando quieres que te ayude. 
You shouldn’t have lied to me, moreover when you want my help.

Other Useful Transition Words to Add an Idea:

De todas formas (maneras, modos) 
In any case, anyhow

De cualquier manera
In any case, anyhow

Sobre todo
Above all, especially

Y
And

If your goal is to be fluent in Spanish, transition words are a crucial area of study. For that reason, it might be a good idea to keep the following list at hand, as you will always need a good transition word to make your speech and writing sound more natural.