Most antique sideboards and buffets average around 50 to 75 inches wide, so you'll need to measure and decide where to place your sideboard accordingly. Per Rodney Lawrence, if you are planning to put your sideboard in an entryway or narrow corridor, a longer but slimmer buffet is better than a shorter and wider one. Make use of the dimensions you do have. If you have a room with more floor space one way than the other, see if you can angle your sideboard to accommodate this. You'll also need to see how much room is left to pull any included drawers out and if you have the space to do this comfortably.
Unless you are specifically looking for a type of wood, you don't need to worry too much about the material. Antique sideboards and buffets generally are made of either a solid and manufactured wood mix or just manufactured wood. If you wish to paint or think you might re-paint your furniture in the future when redecorating, you'll need to go for unvarnished wood. If this isn't a concern, wood that has been oiled or treated with another varnish is less likely to mark. Bright paint colors should also be treated for good maintenance, though sometimes varnishing isn't needed; for example, if you buy a purposefully distressed piece.
It's rare for an antique sideboard or a buffet to not come with some sort of storage. Many contain slim drawers or an extra shelf beneath, but, for some, this level of storage may not be enough. Depending on the room your sideboard will be in, you'll require different storage levels to suit your needs. If the sideboard is for a dining room, are the included shelves wide enough for all your crockery? As Ken Fulk advises, it's always best to have space left at the top of a dish stack to prevent any chipping or other damage to your dishes when getting them in and out. Alternatively, if your buffet is for a living room, extra nooks will be helpful for storing game controls and other small items.
In general, antique buffets tend to feature more neutral color schemes that are in keeping with their vintage look. You can find more brightly colored sideboards if you wish, though design expert Mark Cunningham recommends sticking to either a light, neutral, or dark wood stain finish for versatility reasons. This way, if you ever decide to switch things up, you're more likely to be able to keep the sideboard you already have rather than needing to buy a new one. Distressed whitewashed furniture would fit coastal and farmhouse décor schemes well, whereas mahogany or reddish-brown tones are best suited to more traditional styles.
When it comes to antique pieces of furniture, many contain small details that give them more of a vintage look. Some things to look out for include lattice work, either on glass cabinet doors or legs, as well as scrollwork or other carving detail at the sides. Scrollwork detail across the edges is also a common addition and will lend your sideboard vintage flair, especially if the pattern features antique motifs like roses. Moreover, per Suzanne Kasler, you should also look at the legs. Leg styles like spindle and cabriole will additionally lend antique charm to your sideboard or buffet.