Do-it-yourself (DIY) projects have their time and place. Several minor home improvement or personal tasks can be completed effectively with just a few supplies, perhaps a brief tutorial, and your own two hands. You’re even likely to save some money in the process! But other specialized undertakings, including major front-and-center home improvement projects, are often worth outsourcing to experts.

If you’re ready to update your wall color, don’t waste time, funds, and resources only to end up with subpar results. When you invest in a professional painting contractor, there’s so much more you stand to gain. For starters, you’ll avoid these top ten DIY painting blunders.

1. Skimping on prep work

While you may be eager to get started on your painting project, it’s critical to set up for success before jumping right in. Many DIY projects lack sufficient preparation — a step that makes all the difference in the final payoff. Painting contractors take painstaking care to clean the surfaces to be painted; remove or sand peeling or cracking paint; remove or cover switch plates, outlet covers, and knobs; and apply primer (or a 2-in-1 paint that contains primer) to provide a smooth, even foundation. All of the above techniques are essential to help your paint adhere and get the most mileage out of your new color.

2. Runny paint

If you’re a first-time painter, it’s easy to make rookie errors when you lack the necessary knowledge and experience. Some of the most common mistakes include oversaturating your paintbrush or roller and failing to blend the paint properly upon application. Both of these moves can lead to runny, dripping paint. While runny paint can be corrected by sanding away drips after they dry and covering with a fresh layer, it’s best to rely on an experienced painter’s expertise. Your project will be completed in optimal time and with superior results, so you can enjoy the room sooner and for years to come.

3. Choosing the wrong supplies

You want to keep your painting project within budget, but if you do this at the expense of quality, you can end up with a shoddy paint job or one that doesn’t hold up for long. It’s always worth investing in high-quality supplies so you can get the job done right the first time. Though it can be tempting to scrimp on non-paint items such as brushes and rollers, applying even the best quality paint with cheap tools can leave behind fibers, lint, obvious roller marks, and more undesirable results. A great contractor comes equipped with an equally great set of supplies.

4. Choosing the wrong paint

The way a color looks on a swatch in the store is almost certain to look different once applied to your walls. Everything from room size to light sources, flooring, and accents can influence tone. Consulting with a professional contractor and trying out several paint samples before committing will get you closest to your desired effect. Beyond color, you’ll also want to avoid sheen faux pas such as using flat paint in high-traffic areas (matte finishes are more likely to show fingerprints and are tougher to clean). Navigate the choice between high-gloss, satin, eggshell, and flat finishes with an expert eye.

5. Leftover paint lines

Painter’s tape is a painter’s best friend for a reason! The blue stuff leaves clean lines and provides a buffer to prevent spots and lines from ending up on the adjacent ceiling and surrounding trim. Clean application is especially tricky in corners. Leave the fancy footwork to the pros.

6. Uneven application

Just as too much paint can lead to visibly runny results, too little paint or inconsistent dips lead to tone and texture discrepancies after the paint has dried. To the untrained eye, spotting the difference between a “too thin” and “too thick” layer can be challenging — and you may not notice until it’s too late.

7. Stains

The occasional splatter is pretty much a guaranteed part of the painting process. Any residual splatters can turn to stains if the surrounding area isn’t thoroughly prepared and protected. When you work with a reliable contractor, you can rest assured that all important nearby surfaces will be covered or wrapped with drop cloths or plastic.

8. Color inconsistencies

Are you familiar with the “boxing” technique? If not, and if your job requires more than one gallon of paint, you may want to leave it to the pros. Boxing is the process of combining paint gallons to blend and match the tone and avoid any discrepancies in color concentration that can occur during mixing. Your contractor knows when it’s necessary and how to execute it properly for seamless color results.

9. Buying too much (or too little) paint

Many factors must be considered when determining the necessary amount of paint for a given project. You’ll need to accurately measure the square footage of the entire surface area to be covered, account for multiple coats, and allow just enough extra paint for touch-ups. If you miscalculate or overestimate, you’ll end up with wasted leftovers that will dry out over time. If you purchase too little paint, you’ll end up making multiple trips to the paint store (which is more likely to leave you with tone inconsistencies if the paints aren’t mixed and integrated through the boxing process described above).

10. Poor technique

By now, you’ve probably noticed a common theme: it’s often best to leave painting to the pros. Ultimately, this all adds up to technique, which can only be acquired through experience. A good contractor knows that painting with haphazard strokes leads to paint lines and otherwise sloppy results. They know to start near the ceiling, work downward to smooth over drips, and then “cut in” with an angled brush to blend at the ceiling. They know what it takes to achieve your vision — from color to finish to application and cleanup. For most interior and exterior painting projects, the blunder-free choice is clear: hire an experienced painting contractor in your area!