What are the steps i should take to paint a metal front door?

Jean, can you tape everywhere where you do not want paint....the handle is up to you, same color or different one, which looks best....Probably you need to prepare metal surface then use a primer before the top coat...JMO

You do not need to remove the door or the glass insert and, if the knob/lock set are metal, then don't paint them. The type of paint you'll need is a quart of an exterior grade - the finish should not be flat (satin is my favorite, but you can use a semi-gloss, too). Clean the door really well and get off all the old oxidized paint. Use a good painter's tape to seal the edge around the window insert. I usually remove the lock and knob/handle - but you can tape around them if you want. Remember to put a drop cloth under the door so that it covers the ground on both sides. I use a shim to keep the door open and steady while I paint and I don't tape around the jamb, but that's a personal choice. I use 2 or 3 thin coats with a brush, letting it dry the amount of time specified on the paint can. I just realized that I assumed this was the outside of the door, but the process is still the same except you don't need to have the door open.

You can mask off the hinges and paint the door as it hangs. Personally I would remove the door knob and lock. If you want to change the color/finish of the hardware you should do that with spray primer and paint. Try to paint the door before the sun reaches it to avoid your paint drying too quickly and leaving brush marks. If you use a foam roller it can help you apply more paint more quickly than a brush alone. The foam roller leaves a slight texture to the paint. If you don't want that just lightly drag the brush over it.

If this is an older steel door with scratches, I would suggest you prime it first with an oil based primer. You can paint over the primer with any type of paint.

No, you don't have to take it off but you can. It will be easier if can take the hardware off but you can mask it all off. I would never paint the hardware. Wash the door with tsp and mask off the window unless you are painting the frame the same color then put the masking tape all around the window, on the glass to keep paint off. Prime with a good primer and paint with with an exterior paint.

I used a roller and brush and it looked wonderful and held up thru many Canadian winters. Good luck. :)