Checking for level and plumb when laying bricks is crucial for ensuring a structurally sound and visually appealing wall. Here's how to do it:

1. **Level**: Use a spirit level to check for horizontal level as you lay each course of bricks. Place the level across the top of the bricks, making sure it's positioned in the center. Adjust the bricks as needed by tapping them with a mallet or adding/removing mortar underneath until the bubble in the level is centered.

2. **Plumb**: Use a plumb bob or a plumb level to check for vertical plumb. Hold the plumb line against the side of the bricks, allowing it to hang freely. The line should align perfectly with the edge of the bricks without any deviation. If the line doesn't align, adjust the bricks by tapping them gently into place.

3. **String lines**: Install string lines at the beginning of the wall and periodically throughout the construction process to serve as guides for maintaining both level and plumb. The strings should be positioned along the edges of the wall and adjusted as necessary to ensure the bricks are aligned properly.

4. **Regular checks**: Continuously check for level and plumb as you progress with laying the bricks, particularly at the corners and at the ends of each course. This helps identify any deviations early on so they can be corrected before they become significant.

By following these methods and regularly checking for level and plumb, you can ensure that your brick wall is built correctly and meets both structural and aesthetic standards.