Keep a good Lent.
The best preparation is to continue the habits of prayer, abstinence and charity that you have adopted for Lent.
Take one of the Gospel accounts of the Lord’s Passion and read and re-read it, using it as Lectio Divina during the week. Possibly use one of the ‘Passion’ Psalms (Psalm 21(22), Psalm 67(68),) as a companion reading. Observe periods of silence and prayer.
Make your Confession and receive Absolution in the week before Palm Sunday.
If you love music, listen to Bach’s St Matthew Passion or his St. John Passion (there are English versions of these) or the set of Tenebrae Responsories by Tomas Luis Da Victoria (There’s a good CD of this by the Westminster Cathedral Choir, with English translations in a booklet. The biblical texts of these are also good material for Lectio Divina.