Unsightly veins on the legs (known as "spider veins") can be camouflaged with long-lasting body makeup specially formulated to cover tattoos, spider veins, scars, stretch marks and bruises.
You'll want to choose a concealer that matches the color of the skin on your legs (this will likely be different from your face). Once applied, body makeup should be set with a powder so it won't come off on your clothes.
Another good body makeup product is Cover FX. Don't want to buy online? Check out Dermablend's store locator.
To remove scars, spider veins permanently, see a doctor about fractional lasers, such as Fraxel. These can be pricey, but in just a few sessions your scars and veins will disappear.