(MONEY Magazine) – The time has come. It's barbecue season again, and this year you're going to buy a real grill. No more of those cheap charcoal grills bought spur of the moment from the local hardware store, the ones that devolved into a monument of decaying steel by the time the next summer rolled around. No more lugging bags of briquettes, cleaning out last weekend's ashes before you can even start, and lighter fluids or chemically enhanced self-starting charcoals. This time, you want something you can turn on, heat up and, in 10 minutes, start cooking with. You want something serious, substantial, a grill to last five or even 10 years. This year, you want to be cooking with gas.

But before you rush to your local housewares superstore or lawn-and-garden center to spend a few hundred dollars, ask yourself, "What do I know about gas grills?" Chances are pretty good that the answer is "Not enough." True, these items have become popular--in fact, sales of gas grills have topped those of charcoal models since the mid-1990s, according to the Barbecue Industries Association. But gas grills are a bit more complicated than charcoal kettles, notes Jim Weatherly, the proprietor of two Barbeques Galore franchises in Atlanta. Even in his part of the country, where barbecuing is a year-round activity, people make poor buying decisions all the time. "Basically," he says, "people don't know very much about grills."

UNDER THE HOOD

For starters, you should be prepared to spend between $350 to $500 for a serious grill. You'll see cheaper models out there, but these tend not to be as well put together, experts say, so you may end up replacing them sooner than you would like. (If you're suddenly wondering how serious you are about barbecue, see the box on the next page for a budget alternative.) Spend more than $500, and you're paying for bells and whistles. And, as with a car, it's what's under the hood that counts.

The first thing you should examine, then, is the surface on which you'll cook your food. Ideally, you want a grid that's big enough to let you cook the food for a small party all at one time. If you're feeding a family of five, a grid of approximately 320 square inches (20 inches by 16 inches) is plenty; it will easily accommodate, say, 10 burgers.

Next: the grid's material. Cast iron is excellent because it holds and transmits heat well, searing your food beautifully. The downside is maintenance: It has to be cleaned and seasoned with oil (olive or vegetable) periodically. Porcelain and steel or stainless steel are good substitutes, as long as the grid's bars are wide and the space between them narrow, so that delicate food like fish or vegetables won't slip through.

Below the grid is the grill's heating system. Even distribution of heat is key to the success of your backyard feast. On a charcoal grill, the placement of the briquettes (the sole heat source) largely determines that distribution.

In a gas grill, two elements work together to accomplish the task: burners and heat distributors. To judge the burners, peer into the grill and make sure they cover the bottom. If they don't, you end up having to juggle food on the grid to get it to cook in the same time. Also, you'll want burners that can operate independently, so you can cook with direct heat or indirect heat, for slower cooking.

Lava rocks or ceramic briquettes serve in part as heat-distributing charcoal substitutes. They also protect the burners from dripping juices: If, say, chicken fat lands directly on a burner, it produces a flame that might set your bird on fire. Traditionalists favor lava rocks, which are porous and absorb meat juices, resulting in a vapor that contributes to that smoky barbecue flavor. But these generally have to be replaced every year or two, so if you're less of a purist, Weatherly recommends using ceramic briquettes. "Just turn them over every six months so the flame below can burn off six months of food drippings," he advises.

The third common heat distributor is a system of molded, tentlike metal plates (such as those in Weber gas grills). If you opt for a grill with these plates, Weatherly strongly suggests you avoid flat ones, which will wear out after a couple of years and can be hard to replace, forcing you to buy a new grill.

EXTRA POINTS

Stick to those basics, and you won't get burned. Those other customers who are testing the hood heft of various models, as if there were a direct correlation between the weight of the hood and the quality of the grill? Ignore them. (Or snicker discreetly.) And don't get distracted by pointless extras. Pass on the window-on-the-hood models. After a few grillings, you won't be able to see a thing unless you clean meticulously after each barbecue.

A couple of final tips for the backyard. First, if you have hosted several barbecues and don't know how much fuel is remaining in the tank, weigh it on your bathroom scale. Experts estimate that you get one hour of barbecuing per pound of fuel. So, for example, if your standard 20-pound liquid propane tank--which really weighs 18 pounds empty and 38 pounds full--weighs 25 pounds, you have approximately seven hours of cooking fuel.

And finally, to make sure that your grill lasts, you should buy a grill cover. "You can get them for anywhere between $20 and $50 for generic ones or up to $70 for a brand-name cover, but it's worthwhile," says Weatherly. "It's like garaging a car. It just helps it last longer."