Does your kitchen already have ducting? If you already have ducting installed, this could save you a lot of time and money in installation costs. Be sure to get measurements on your venting system to make sure the new range hood's specifications match what you already have.
Do you want to install ducting or get a non-ducted range hood? You can save a lot of money by installing a non-vented range hood. However, experts strongly recommend using a ducted system if at all possible because it takes smoke, odors, etc., outside instead of filtering and then recirculating them in the kitchen.
Make sure to vent to the outside. When installing a ducted hood, never exhaust air or terminate ductwork into spaces between walls, crawl spaces, ceilings, attics or garages. All exhaust must be ducted to the outside. If it isn't, figure in the cost of correcting this.
What's your kitchen design? Whether you are remodeling a kitchen or building one from scratch, the location of your cooktop or range will determine what type of range hood you install. If the cooktop is on an island, you'll need an island-mounted range hood. Cabinets above the cooktop? Go for an under-cabinet range hood. Is the area above the cooktop clear? A wall-mounted range hood will work.
What style and color are your appliances? Make sure your new range hood comes in the style and color of your kitchen. Some manufacturers offer a variety of colors, while others focus on stainless steel.
Check your clearances. Range hoods need to be installed high enough to not cramp your style when you are cooking, but not so high that smoke and vapors have a chance to escape its pull. ConsumerReports.org notes that most makers specify a clearance of 18 to 30 inches.
Check your ceiling. Wall-mounted and island range hood have a chimney that rises from the hood to the ceiling. Most are designed to accommodate typical kitchens, but you can run into issues if your ceiling is either too low or too high. Check the manufacturer specs to see the chimney length, adjustment range, and the availability of accessories to deal with difficult installations (a chimney extension, for example) of any wall-mounted or island range hood you are considering.