Straight-line quilting was the first kind of machine quilting I got genuinely comfortable with, and it's still what I reach for on most quilts. It doesn't require the hand-eye coordination that free-motion work does, it finishes fast, and on a modern quilt with clean piecing, straight lines look intentional rather than like a compromise. But "straight" only stays straight if the machine is feeding all three layers of the quilt sandwich evenly, and that's where a standard presser foot lets you down.
Why a walking foot, specifically
A regular presser foot has feed dogs doing all the work underneath, dragging the bottom layer of fabric through while the top layer gets pushed along mostly by friction against the foot. That's fine for piecing two layers of quilting cotton. It's not fine for a quilted sandwich — top, batting, and backing — because the top layer and bottom layer are no longer moving at the same rate. The top creeps ahead or lags behind, and the excess has nowhere to go but into little puckers and tucks along the stitching line.
A walking foot, sometimes sold as an even-feed foot, solves this by adding its own set of feed dogs on top, synced to the machine's bottom feed dogs. Top and bottom layers move through together, at the same rate, so the fabric isn't being asked to stretch or bunch to keep up. If you've ever quilted a straight line on a standard foot and watched a little wave of extra fabric pile up ahead of the needle, that's the exact problem a walking foot is built to prevent.
Marking your guide lines
Straight-line quilting is only as straight as your guide. For simple grid quilting, painter's tape (the thin quilting variety, about a quarter-inch wide) laid directly on the quilt top gives you a stitch-beside-the-edge guide you can see clearly and peel off without residue. For a single long line — quilting in the ditch along a seam, for instance — many walking feet accept a quilting bar attachment that rides alongside a previous line of stitching, keeping every subsequent line evenly spaced without any marking at all.
If you're marking directly on fabric, use a tool you've tested for removability on a scrap of your actual backing and batting combination first, not just the top fabric. Some marking pens behave differently once they've been sandwiched against batting and pressed by the friction of quilting.
Managing the bulk of a full quilt
This is the part nobody mentions until you're fighting it: a home machine has a small throat space, and once you're quilting the center of a queen-size quilt, most of that quilt is bunched up to the left of the needle, and it's heavy. The trick isn't strength, it's arrangement. Roll or fan-fold the excess quilt tightly and use bicycle clips, large safety pins, or quilting-specific clamps to hold the rolls out of your way so they're not dragging against the machine bed or pulling the section you're stitching.
A table extension around your machine — even a simple flat surface that brings the sewing surface level with the machine bed — makes an enormous difference here, because it gives the bulk of the quilt somewhere to rest instead of hanging off the edge of a small table and pulling on whatever you're currently stitching. I didn't believe this mattered until I quilted a lap quilt without one and then quilted the next one with a card table butted up against my machine table. The difference in how evenly the fabric fed was immediate.
Start simple: grids and diagonals
The easiest straight-line quilting to start with is a simple grid or a set of parallel diagonal lines across the whole quilt, stitched from the center outward in both directions so you're always working with the bulk of the quilt evenly distributed rather than all piled on one side. Quilting in the ditch — stitching directly along existing seam lines — is visually the most forgiving option for a first project, since minor wobbles hide inside the seam itself rather than sitting exposed on open fabric.
Resist the urge to attempt anything curved until straight lines feel automatic. Gentle curves are technically possible with a walking foot, but they ask the foot to do something it's not really designed for, and the results are usually disappointing compared to what a walking foot does well. Save curves for free-motion work, and let the walking foot earn its keep on grids, diagonals, and in-the-ditch lines first.
Basting still matters here
A walking foot prevents puckers caused by uneven feeding, but it can't fix puckers caused by a sandwich that wasn't basted well in the first place. If the layers can shift against each other before the needle ever gets there, no foot will save you. Baste generously — pins every four to six inches, or a spray baste applied in thin, even layers — before you start quilting any line, straight or otherwise.