Decide on the location and the width of your new gravel pathway. When you have decided where it is going, draw the outline of the path with spray paint. This will give you a better visual of where the path is actually going.
Dig the area between your outline down to a depth of six inches with a shovel.
Tamp the soil down with a hand tamper to create a solid base to work on. Add three inches of loose soil around the edges of your trench and an additional inch of soil along the rest of the trench.
Carefully spray weed killer in to the bottom of your hole, doing your best not to get it on the surrounding vegetation. Make sure to follow the directions listed on the weed killer so that you spray the right amount to sufficiently kill all the seeds in the soil.
Lay out landscaping fabric along the inside of your path, being sure to coat the bottom completely. If you need more than a single run to cover the entire trench, be sure to overlap the edges of your fabric by at least three inches to create a tight seal.
Stand a pressure-treated two-by-six on its narrower edge, and pound it into the soil with a mallet along the edge of the trench, making sure that the board stays straight. Continue this process along either side of the trench. Cut the last two-by-six so that it fits in the trench perfectly. Don't block either of the ends of your trench as these spaces will be where water drains out.
Add sand over the top of the landscaping fabric. Add a few inches at a time, and tamp it down until you have a solid two-inch layer.
Add the gravel that you picked out into your trench a few inches at a time. Tamp the gravel down, and add more if needed, continuing the cycle until the gravel level is half an inch below the two-by-six edging.