Hey grown-ups, Halloween is for you, too. And it’s frightfully easy and affordable to jazz up a store-bought costume with these accessorizing tips.

Add some ’80s-inspired accessories to an ordinary princess costume for a totally tubular retro vibe. Crimp your hair, then pull it into a side ponytail. A coordinating scrunchie can secure it in place. Add retro makeup, too. Think light-pink lipstick, lots of mascara and dark-pink blush.

Vampire teeth and an “axe-to-the-head” accessory sure change a regular superhero costume. Want to go from heroic to freaky? Glue plastic bugs on your costume’s tights.

Glue various color streamers inside a large pastel or white umbrella. Let the streamers cascade around you; they’ll look like tentacles! Your revamped mermaid costume will shimmer and shine.

Create a large cardboard frame and decorate it to look like a computer screen. Then, position the frame so that your head is the picture inside. Wear an old, white T-shirt and bring markers. Your friends can write “online” comments!

Today’s vampires are much less obvious than yesteryear’s. Go to parties in your most stylish suit or jeans outfit — and keep your fangs well-hidden. Dark eyeliner and gray eye shadow help create sunken, dead-looking eyes. A wine-goblet accessory filled with tomato juice complete the vampire look.

Be a ghoulish chef — wear a chef’s coat, hat and black pants. Want a ghostly hue? Spread white powder on your face and hands. Glue plastic food to a tray and carry it with you.

This costume requires three people. Cut holes out of three 55-gallon garbage bags — you’ll place your head and arms in there later. Use craft paint to write one word on each bag: “garbage,” “recycling” or “composting.” Then, glue empty bottles and cans to the recycling bag, plastic wrap to the garbage bag, and faux fruits and vegetables to the compost bag.

Got a Cat Woman costume? Remove the tail and paint your fingernails black. Apply pale face powder, wear a long, black wig and carry a dried-flower bouquet.