The ancestral altar is one of the core components of many forms of witchcraft and shamanism. One of the earliest forms of spiritual practice, ancestral veneration is one of the fastest and most potent way to get your 'friends on the other side.' The actual implementation of the altar is fairly simple, too, and unlike many forms of altar, these can be openly displayed in the home easily, not just in the sense of a focal point for the living family, but for those more 'in the closet', it can fit well with the Live, Laugh, Love aesthetic. The best first step would be to set aside a table or shelf of some kind that will serve as the altar itself. Cover this with a white cloth, and put pictures of your deceased loved ones. I personally like to have family members closer to me on the tree closer to front and center, but this is not necessary. You can also add living family members as well, if you so wish, though I do not. If you don't have pictures, you can also print out a family tree to place on your altar. With your pictures in place, the next step is the offering dishes. I like to reserve one chalice (in my case, a wine glass) and one plate that stays on the altar unless it is being cleaned. This is not used by anyone else in the family, and is reserved for the ancestors. I use a plain white porcelain plate, as it is simple and straightforward. I also like to include white candles. Novena candles are a personal favorite, but you can use anything for this. I also like to include a plain, unadorned incense burner. The key factor to your decor is that it is simple. White cloth and candles, because white is the most generalist color. Plain candlesticks, incense burner, chalice, and plate, so that everyone may equally partake without feeling as though you are favoring one member over another. Once you have your things assembled, you can start making your offerings. Again, the key is simplicity: water, pound cake, white candles, and floral incense. Nothing too fancy, except as a special occasion. But making these simple offerings once a week will build your connection. Once you've made a habit of making weekly offerings, the fun can begin. Make your offerings and just sit, enjoy their presence. Your ancestors will settle into the schedule, showing up for their offerings and hanging out a bit, and during this time, you can commune with them in quiet meditation, or even use cards and other tools to communicate with them.
Once you've built the connection, you can use this altar for working with specific ancestors if you so wish. When doing this, change your altar up to meet your needs. Exchange the white cloth for one in their favorite color, bring their picture front and center, offer their favorite drink and food, burn incense they would enjoy, and change your candles out to something more in line with them. Then, when you make your offerings, call to them specifically and ask them to be present with you. It is not an overly complicated practice, but it does yield a great many benefits.
Now, a question I get asked frequently is, why give offerings to spirits? They do not eat the cake or drink the wine, so what good does it do? Well, aside from imbuing the offerings with your personal energy by the act of giving them, they do eat the food, in a way. They take in the essence of what is offered to sustain them. This is why with some spirits, the offering changes depending on what you need. For instance, if I am at my altar asking for money, I offer something sweet and smooth, like mead or brandy, so that the same energy is imparted to my spirits for their work and so that the money is not painful to acquire. If, on the other hand, I am asking for the death of my enemy, I might offer boiling chili oil or water taken from a stagnant puddle. The essence of the offering matters just as much as the act of giving it. So, in short, by making an offering, you are imparting a sympathy to the spirit they can use to your benefit.
These and other topics related to spirit work can be found covered more in depth in my book, The Spirit Work Primer Second Edition, available for preorder now through my publisher: https://crossedcrowbooks.com/product/a-spirit-work-primer-a-beginners-guide-to-streamlined-spirit-work/