This photo is my altar for a holiday sumbel and blot, such as Yule. Sumbel is the toasting and blot is the blessing.
Altars for different purposes will have different things on them. This one is a portable altar used for community ritual. A permanent altar dedicated to a god or ancestor or to the gods generally, also called a shrine, would generally have fewer working tools and more symbols, and would probably include representations of the gods or other beings to whom it is dedicated, such as statues or pictures, and possibly sacrifices to them. Some Asatruars keep shrines and some don't, but any Asatru community ritual includes a sumbel, and most include a blot.
The altar for a sumbel has to include something to drink since sumbel is a toasting ritual. Asatru uses a drinking horn for this ritual. We use a cow's horn to honor Audhumla, the sacred cow who was the first self-aware being. Our mythology says that before time began or the World Tree grew, Audhumla licked the gods and the giants out of the ice and nurtured them on her milk. So a cow's horn represents the Great Mother.
There are two bottles and two horns on the altar in this picture because one bottle and horn set is for alcohol and one is for a non-alcoholic beverage. This altar also contains a bottle opener. This isn't a dedicated holy bottle opener, just the normal one from my kitchen, but being used for ritual means this opener is going to have a bit of specialness about it even after being returned to normal use. It is traditional to toast with mead, but other beverages work, too.
The altar for blot almost always contains all the things for sumbel as well because sumbel usually comes first and then blot. In the old days, the blot bowl caught the blood of a sacrificed animal, keeping the blood from touching the ground, and then the blood was sprinkled over the participants to bless them. In modern times, the bowl is partially filled with water, and then the dregs of the horn are poured in the bowl after the sumbel, and the mead / water mixture is sprinkled over the participants to bless them.
The pine branch on the altar is the asperger, which is used to sprinkle the water onto the participants. This pine branch is from a sacred pine tree I maintain at my home for this purpose. Before the main ritual, I ritually cut the asperger from the tree with this ritual knife. The knife can then go on the altar, on my belt, or can be put away.
This basic altar contains only the things necessary for the ritual. It can also be decorated with seasonally appropriate decorations, symbols of the gods, and anything meaningful to the godhi or gythia (the conductor of the ritual) or to the ritual participants.