1st Stage
The first stage of Frieza is very weird. he's so small and ugly but is so strong. He normally flies around in a little pod thingy. This is his weakest form, also his body shape is very weird as well.

2nd Stage
This is the stage were Frieza goes huge! He kills Krillin in this form and is also very slow. He gets a lot more muscle power. He is allso very taller and takes a more human form. He fights a lot in this form but changes pretty quickly after giving the fighters a big fight.

3rd Stage
Frieza gets way more stronger but looks like a dumb ass. his head gets so fat and long it's not funny, and he totally stops taking a human form and takes some very weird alien form. He doesn't stay in it for to long.

4th Stage
The final stage! He gets very fast and strong and gives a lot of trouble to the z fighters. He takes a human form perfectly at this pint, and is so much stronger. He improves everything at this form and pretty much dominates the battle until Goku goes Super Saiyan.