Lectio Divina is one of the great methods of mental prayer (meditation), but there are many different ways to do it. i would suggest getting a good book on spirituality. right now im going through Introduction to the Devout Life by St. Francis De Sales, and i know he has a section on mental prayer as well as a few meditations that he recomends going through. another classic meditation book (note: not a book on meditation, but rather makes a good subject for meditation) is * The Immitation of Christ.* ultimately you will have to try it for a bit till you get used to it.
also, i cant recomend Eucharistic Adoration highly enough. you should ideally practice mental prayer (or any type of prayer for that matter) in Adoration.