Real estate signs are not a "one size fits every situation" sort of thing. In fact, there are four types of real estate signs, each with a slightly different use. Those four types of signs, ranging from basic to best, and what you can expect from each, are as follows.
The Basic Sandwich Fold-up, or "Teepee" Sign
This is a tiny little sign that folds out like a triangular tent and just sits in your yard. It lists the very basic information about your home or property and who to call for more information. While it does a decent job of showing people that you are selling that property, this basic sign has a tendency to fall over in the wind. Sometimes kids in the neighborhood will come through and kick it over too. For that reason, you might decide that one of the other three types of signs is a better option.
The Banner Sign
A banner is hung across the front of the house or building or strung between two poles in the yard. The banner may be vinyl, or it may be lightweight polystyrene mixed with cardboard. There are advantages to both. The vinyl one will hold up in even the worst rainstorms and not be ruined, but it can and will flap crazily in the wind. The polystyrene/cardboard one will only hold up so long in wet weather conditions, but it is heavy enough that it will not flap in the wind quite so hard. Both may come loose in a really bad windstorm and fly away, but that does not happen all that often.
The Metal Frame and Plastic Sign
This type of sign is only slightly larger than the basic sandwich/teepee sign, but it is much more durable. The metal frame is black-painted steel, and it uses either grommets and zip ties or a center casing for the sale sign made of hard plastic. It cannot blow away in the wind, it withstands all kinds of weather, and you can print sale information on it on both sides to grab attention from coming and going traffic on the street. The only downside is that you do have to hammer the vertical steel tubing into the ground.
The Best of the Best: Semi-Permanent
This is the traditional real estate sign made of either a metal or wood post, a single arm that juts out, and the free-swinging plastic sign that hangs from the arm. The reason why these are semi-permanent is that quick-drying concrete is used to root these signs in the ground. Once your property sells, the concrete and the sign come up out of the ground, and soil and grass seed fill in the hole that is left. However, absolutely nothing moves these signs (short of sinkhole opening beneath them!), and everybody can see that your property is for sale, who is selling it, what it costs, where it can be viewed online, etc.