The Holy Spirit guides you and empowers you. There are two types of tongues. Public tongues and this is meant for a church to encourage them. It is God speaking to a church for them to be edified and requires an interpretation. The other is devotional tongues which is you speaking and praising to God, doesn't require translation and will edify and encourage you. 

Why speak in tongues daily? It expresses worship, it expresses effective intercession (when you don't know what to pray, the spirit prays through you because it knows what's in your heart. Sometimes you will pray for other things happening around you that you don't even know what is happening.) It expresses the mysteries of the divine. Lastly, it expresses confidence.