I am a reader (not an “(instituted) lector”, which is a particular ministry in the Church) at my parish. Here is my advice to you:
First, pray. I have a prayer to the Holy Spirit I can share with you. Pray for assistance from the holy authors of Scripture. Pray for assistance from your guardian angel. Pray to Jesus that he, the Eternal Word, might be present to you as you proclaim the written word.
Second, read. Practice reading the Scriptures out loud several times. Know what words you’ll need to pronounce carefully – don’t let the phrase “in fidelity to” sound like “infidelity to”! – and where you will need to read more slowly than you are accustomed to. Practice the difficult words – Nebuchadnezzar, Melchizedek, etc. Be sure you speak clearly, slowly, and audibly. Breathe regularly!
Third, study. Know the context of what you’re reading, as it will help it make sense to you and give you more ideas as to how the reading is meant to be proclaimed.
Here’s the prayer I pray every time I’m going to proclaim the Scriptures at my parish:
I beseech you, Holy Spirit,
to be in my heart and on my lips,
that I may worthily and fittingly proclaim the word
which you inspired in prophets and apostles,
to the glorification of God and the sanctification of His people.
Through Christ our Lord.
Amen.