Several options are available for flutes. Here are some general rules of thumb to consider:

Body and Headjoint

Silver Plate and Solid Silver
Silver plate and solid silver are considered to assist in projection of sound. Solid
silver will be superior in wear, projection and more importantly tone.

Gold Lip Plate
Gold lip plates will not tarnish due to use. Some people also believe it assists play with a richer tone.

Cuts&Tapers
Flute headjoints that are solid silver are generally available in different lip plate cuts and inner bore tapers for the individual tastes of the musician. There is a also normally a charge that applies to the selection of a non-standard headjoint.

Toneholes and Keys

Drawn toneholes
Drawn toneholes are superior because they are continuous with the body of the flute. No harmonious vibration is lost due to a soldered joint. Of course it's more difficult and therefore more expensive to assemble instruments in this fashion.

Open-holed Keys
Opening in the center allows for better projection uncovered, and half fingering when covered.

"Gizmo" key
"Gizmo" key allows for easier play of the high "C" by changing the airflow within the flute.

Footjoints

C Footjoint and B Footjoint
The C footjoint is the standard footjoint found on a beginner's flute. The longer B footjoint joint not only adds another note to the low end of the flute's range but also assists in projection.