To cut slate tiles, you will need the following tools:

- A tile cutter or wet saw
- A straight edge or ruler
- A pencil or marker
- Safety glasses
- A dust mask
- Gloves

Here are the steps to follow:

1. Measure and mark the slate tile where you want to cut it. Use a straight edge or ruler to make a straight line.

2. Put on your safety glasses, dust mask, and gloves.

3. If using a tile cutter, place the tile on the cutter and align the mark with the cutting blade. Score the tile using the cutter, applying firm and consistent pressure to the handle. Score the entire length of the tile.

4. Once the tile is scored, use the tile cutter to snap the tile along the scored line. Some tiles may require light tapping on the underside to break them fully.

5. If using a wet saw, fill the saws reservoir with water and turn the saw on. Place the tile on the saw and align the mark with the saw blade. Adjust the saws cutting depth as needed.

6. Slowly and steadily move the tile through the saw, making sure to keep the blade aligned with the mark. Let the saw do the work and dont apply too much pressure.

7. Once the tile is cut, turn off the saw and remove the tile from it. Clean up the area and remove any excess dust.

Remember to always wear proper safety gear and practice caution when working with any cutting tools.