What to Meditate On
In general, any virtuous object can be used as an object of meditation.
If we discover that by acquainting our mind with a particular object our mind becomes more peaceful and virtuous, this indicates that for us that object is virtuous. If the opposite happens, for us it is a non-virtuous object. Many objects are neutral and have no particular positive or negative effect on our mind.
There are many different virtuous objects of meditation, but the most meaningful are the twenty-one objects of Lamrim meditation. CLICK HERE for what to meditate on.