Easy-to-make Greek costumes are excellent if you're going to a toga party or would like to dress up as a Greek goddess on Halloween. They're as simple as can be and can often be created using items that you have around the house, making them cost-effective as well. If you're going with a Greek god as a date, his toga can be made in pretty much the same way.
Wrap a sheet around you by first stretching a large white bed sheet horizontally and hold it behind your back. Hold up the corner of the sheet with your right hand and bring it up to the right side of your chest. Wrap the left side of the sheet around your body and bring it up toward your right armpit. Drape it over your right shoulder, meeting with your right hand.
Pin the sheet in place using safety pins, making sure to not stick yourself with them or place them in a spot that's going to be uncomfortable for the entire night. Use enough pins so the sheets will be secured and stay in place for hours.
Tie a thick gold rope or piece of yarn around waist, tying in the front with a lot of excess hanging down.
Wear simple sandals in brown or tan. Lace the gold rope or yarn through the sandals and up your legs, tying it right below the back of your knee.
Pile on gold jewellery -- the chunkier the better. If you have larger bracelets that typically hang loosely on your wrist, move them to your upper arm if they'll stay positioned that high.
Add props to become a specific Greek goddess. For example, if you want to portray Athena, carry a spear and walking stick, and adorn your head with a wreath made from fake leaves. Add a splash of colour to channel goddess Iris. You can lace your hair with coloured ribbons or wear colourful jewellery. Swap out the gold cord for one in a colour from the rainbow. To become Aphrodite, wear tons of bright, glowing make-up.
If you want to show off as little skin as possible, find a white sheet and cut three slits in it for your head and arms instead of simply wrapping it around you. Wear shorts and a strapless bra under the sheet to make sure that you're covered in case any part of your costume comes undone.