To ensure that your wood fence posts are level and aligned, you should start by marking the layout of your fence with precision. Use stakes and string lines to outline where your posts will go, ensuring theyre evenly spaced according to local regulations and personal design. When digging the post holes, they should be at least one-third as deep as the height of the post above ground for stability. As you set each post into its hole, use a level to check that its plumb on all sides. Brace each post with stakes or temporary supports while you fill the hole with concrete or gravel mix, checking the alignment again before it sets.