You should not read each slide word for word, but use the key points on them to support what you are saying. Point to the key point on the slide you are taking about. Refer to the slides in appropriate places. So neither ignore your slides or use them as a crutch for an unprepared presentation. Use them as support and integrate them into your teaching.
Technology can fail.
Back-up everything you do on a computer at least twice. Bring two separate disks with your completed presentation on them in an appropriate safe carrying case. Do not let a corrupt disk ruin your day. Pace -speak slowly and clearly. Eye Contact -look at your audience.