[NEWBIE]Recently started practicing Pixel art, would like some feedback and tips

[Nagariku]

Just recently started a few days ago and have some questions about pixel art in general. The sprites are in order of when they were made.

Dragonslayer sword from manga "Berserk"



My submission for @pixel_dailies on twitter for "Princess Mononoke" day



My submission for @pixel_dailies on twitter for "Drill" day, which was yesterday




Any tips and critique are welcome.

Questions:

Should I take measurements before starting to do the sprite, for example if I do something like a knife or should I train my eye?

I have trouble doing large sprites that have irregular shapes, such as oval, circles, should I easy into it slowly or just start doing them with "fake it till you make it" slogan?

Should the borders be the same colors as the pixels inside? For example if I do am orange circle, should I have black borders or orange borders? What about smaller shapes inside the circle?

P.S. First time posting on any forum

[Nagariku]

Also, the spear and a drill are a bit wrong at some points some squares are not the colour they are supposed to be, should I post the enlarged version as I had to make it smaller without remembering precise numbers

[Koyot1222]

Maby this would help 

[Nagariku]

Maby this would help 

Do you think it should have emphasized edges?