I know mild steel welding quite well,....done it all my life.
Arc welding in a shop is almost obsolete anymore, but they still have their place.
Mig welding is easier, and cleaner.
I would recommend a smaller Mig machine of 130 amp mininum, which will run on 220-240 volts. IMO, don't buy a 115 volt Mig machine, or you will be limited to ......like 1/8" material.

A HF machine (china) Mig welder may be ok,.....I haven't used one, but I would recommend a Hobart, Miller or Lincoln,....all in the smallest 230 volt will do you a good job on 1/4 - 1/2" steel.

Mig machines can be run 2 ways, either using solid steel wire w/ a bottle of Argon sheilding gas mixing w/ the arc, or using flux core wire.
Using bottled gas is much cleaner than the flux core, but both do better than an Arc welder.

I myself have a 135 amp Lincoln w/ Argon gas, cost around $500.
The china machines are less than 1/2 that price.

Hope this helped you a little

On edit, any good Mig machine can be converted to weld stainless steel just by changing your roll of wire to SS. The gas should be changed too, but doesn't have to be.

Your best bet for just learning (in my opinion) would be to start with mig welding.if you have a harbor freight tool store close by you can buy a flux core welder for about $100.a flux core differs from a standard gas shielded mig welder in that it uses a core in the wire that releases the shielding gas as the wire burns.I recommend it because you won't have to worry about having compressed gas cylinders around.start with some light duty welding to get the feel for it,when holding the gun try using your free hand as a base to steady your welding hand with.it's all about keeping the gap between the tip of the welder and the metal consistent along with a steady speed as you move along the weld.arc welding with welding rods (to me) is trickier in that you not only have to keep the arc gap and speed consistent but you also have to move the rod down as it melts away.Start by going to http://www.millerwelds.com there's a ton of useful info to get you started.

Thanks for any new information.

I'm happier than a pig in slop with my Miller 211, running gas.  It was expensive, but it's got plenty of power and selects the wire feed rate and current for me.  Not a whole lot else to screw up.. though I try..

I acquired the $179 Harbor Freight inverter (DC) arc welder a bit ago for small repair projects.  I've fixed a few things at work and a part on a friend's motorcycle with it.  From what I can tell, shielded metal arc welding is kind of messier and considered more archaic than MIG or TIG, but I specifically purchased this particular welder because it runs on regular household power.  No problems so far other than my own skill level.

Great question and great answers.  I have always wanted to give welding a try also.

I agree with the previous opinions, MIG is the best way to go these days for general purpose welding on steel but keep in mind that inexpensive welders are more difficult to use.  I have a friend that does most of my welding for me and he has sold all his welders except one Miller MIG welder.  I was a certified welder in my youth and learned in a well equipped company with a variety of different welders.  This was a good way to learn, better yet is at a local community college.  They usually have quality welders of different types and makes and you will not only develop your skills but preferences for different welders.  If you self teach yourself welding you will likely learn to do some things well but you will never know what you have missed.

Stick welding is still effective and you can buy rods of various diameters, materials, and for different weld positions for a wide variety of weld situations.  I still keep a stick welder at home for odd jobs, an old Miller.  It takes up little space and I don't have to worry about gas cylinders.  If I were you I would rather buy a used quality welder than a new import welder.  So many companies have folded recently that used welders are going pretty cheap.