Hands are complicated 3D shapes with many degrees of freedom of movement. Gloves need to accommodate this and are as such more complicated than 2 pieces of hand-shaped fabric sewn together.
-duct tape (or something similarly flexible)
-paper (preferably tracing paper or something similar)
-a disposable glove (latex, nitrile, whatever you have on hand [HURHUR])
-a permanent marker
-Fray-Check (optional, but nice to have)
-a sewing machine and/or a needle and lots of patience
Step 1: Terminology and Key
Fourchettes - the little pieces of fabric that go between your fingers
Thumb - the part that goes on your thumb (derp)
Fourchettes are one of the most overlooked parts of gloves, but they are VERY important for comfort and mobility of your fingers.
-darker fabric color is the "right side", or the side of the fabric that you want on the outside of your glove
-lighter fabric color is the "wrong side", or the side of the fabric that you want on the inside of your glove
Step 2: Drafting Your Pattern
Put the disposable glove on your non-dominant hand (I'm right-handed, so I put it on my left hand), and layer strips of tape all over the latex glove. Have a friend help you cut tape strips if you can, it's a lot easier that way. Make sure you get a nice, thick layer all over your hand, especially between your fingers and around joints.
Once you have coated your hand in tape, trace a line from the tip of your pinkie, down the side of your hand, to your wrist. This will be your trank seam.