1st- Solid Wood vs. Hardwood vs. Engineered Wood
People like to use these interchangeably, but there is a difference and you should know how to spot it.
Solid wood-is basically any kind of lumber and is NOT engineered wood. Examples of solid wood are pine, birch, maple, oak, walnut, mahogany, cedar... lots more than I'm not gonna name... Basically when you cut it, you can still seen the grain throughout.
Or if you are looking at the side of a drawer, you can see the grain. Sometimes even solid wood dressers will have a wood veneer on the front... usually because they want something that has a prettier grain than what the piece was structurally made of. These are still good because even if bits of the veneer are missing, you can patch it up with wood filler, sand it down, and paint over. Overall the piece is usually sturdy and long-lasting, but you will not be able to sand it down and stain it something else if bits of the veneer are missing. Once you patch it, you will have to paint it.
Hardwood- is a select type of solid wood. Hardwoods are generally the nicest and heaviest of woods and also last the longest. They are in general harder (less porous) than softwoods. Examples of hardwoods include mahogany, walnut, maple, oak, birch and cherry. Softwoods are lighter and a little less durable (examples are cedar, pine, spruce). Anything made of hardwood is going to be more expensive usually because it is nicer. A solid oak or mahogany dresser at a good price is not something to pass up. Even if there are some minor repairs... if the majority of the wood is undamaged and structurally it is sound, get it!
Pretty much any time of solid wood is sandable and stainable, as long as there is no veneer. Keep that in mine when you decide what your vision for the piece is.
Engineered Wood- is anything made from particle board/pressboard/compressed wood or MDF. MDF is better than particle board because it is stronger, but they are both (for the most part) less expensive than solid wood because they are cheaper to make/produce.
Particle board (which is a composite of wood chips/sawdust and resin) and is also referred to as compressed wood or pressboard. It is often very heavy (which can be misleading) and is usually disguised with a plastic veneer. This CANNOT be removed to sand and stain the wood underneath. Don't try. You will be sad.
Engineered wood is terrible once it is wet. It will almost immediately bubble up or expand in places and looks horrible, which is why there is often plastic veneer (that often looks like wood) on places that get a lot of wear or could be exposed to moisture. This is what A VAST MAJORITY of furniture these days is made of.
This is often what I first look at when I see some piece of furniture that I like. A quality piece of furniture is going to have good joinery. It is a sign of good craftsmanship.
Dovetail joints: When 2 pieces of wood are joined together perpendicularly and do not require nails. This is commonly found in drawers. Unevenly spaced dovetails or unequal size dovetails usually indicate it was made by hand (more common in furniture from mid-1800s).
Tongue and Groove joints: When two pieces of wood are joined together side by side. This is commonly seed on wood floors, but is also seen on the tops of dressers or tables.
Mortis and Tenon joints: When the top or short part of a board is being joined together with the long side of a board and a "pocket" or Mortis is created to fit the other board. This is commonly found in the "bones" of a dresser (structural areas). This type of joint is found in drawer glides, and in the framework around each drawer spot/hole.3rd: Shape/Curve
This is the decorative part of furniture. In my opinion, really great furniture will have some curves. Maybe it's on the legs or maybe it is the way the drawers bow out or have a serpentine, or maybe it's a bombay chest and it curves out like a woman's hips on either side of the chest. Or maybe it is kinda boxy but it has some nice carved areas or relief work or wood applique. Those all add character and can be highlighted with a good finishing technique (stain or paint).
This is not always a must, but sometimes if you find a piece that has great original hardware (meaning drawer pulls, knobs, or keyholes), it is worth buying! Good hardware is almost always heavy, indicating the type of metal it is made of. Brass, cast iron, and steel are all examples of types of metal that hardware is made of.
ALSO let's not forget my favorite GLASS knobs or ceramic knobs! They are quite charming and often very expensive if you buy them online. Look for something pretty, carved, decorative, unique in some way. Even if the furniture you found it on is completely trashed beyond repair, you can harvest the knobs and either sell them on ebay or save them for a future project that has sad (or no) knobs/pulls.