What are you short and long terms goals and long term budget? I ask because hot lights look like a cheap entry point for lighting but aren't very practical for several reasons: intensity, heat, safety hazards.
I don't presume to know which solution will best meet your goals, but I hate to see you waste money on a something you think will work but will later abandon. Flattering lighting starts with knowing how to put and effective highlight pattern on the face - one that creates a natural 3D appearance in a photo - then finding the most flattering camera angle for the face (both vary face-to-face).
Window light and a reflector is a better short-term solution for learning the basics of lighting than hot lights. Its how I learned from a PPofA Master and all the lessons translated over to using flash. See these tutorials of mine on window lighting and the basics ofartifical lighting and you'll see the similarity.
You can also get a set of Alien Bee studio flashes and modifers within your $750 budget, but you'll probably get more use out of a hot shoe flash solution. I have both and use the hot shoe flash 10x more often than the studio lights because most of the shooting I do with flash is either location candids or outdoors where a pair of hot shoe flashes is more practical. Once you understand how to light a face it can be done just as effectively with almost any tool, anywhere.
See this tutorial of mine for an idea of what is possible with a pair of Canon flashes.LINK Also see this recent thread where I posed about a dozen examples showing the range of things possible: https://www.fredmiranda.com/forum/topic/842938/3#7861732
thanx chuck^^^ I have a 420ex been looking for a 550ex or a cheap 580ex2 your tutorial looks like it will help me alot,just want my pics to look like they wernt taken with a P&S
The flat "deer in the headlights" look of on camera flash, particulary in portrait mode, is the a result of the angle of the light being too low relative to the face. Natural light comes from overhead most of the time which is why a face lit from overhead and the side (about 45 degrees from the light source) looks 3D and natural and light hitting from eye level or below look artificial.
Once you grasp that raising the light is best way to improve results with your 420ex, a wise move to leverage what you already have would be to get an OC-E3 cord and camera-flip bracket, which raises the flash high enough to create a flattering downward pattern, but not so high the brow begins to shade the eyes, which often occurs in both natural light outdoors and with flash bounced off the ceiling.
Look for a used 580ex. Its the ideal unit for a Master because it has an Off (solo use) / Master switch on the base making it easy to alternate between one and two flashes when a slave is used. The 420ex is ETTL, which is OK as a slave, but any of the other models (550ex / 580ex / 430ex/ and mkII's) which also suppport shooting in manual flash mode are better for static situations like portraits.
BTW- the solution for dark eye sockets isn't adding "fill" flash, but simply getting the person to raise their eyes up into the same "key" light which is hitting the forehead and cheek. The problem is the brow shading the eyes. The solution is to move the brow so its not shading the eyes, then get up on a ladder or chair to raise the POV of the camera by the same amount.
With your budget, consider an Alien Bees B800 if shooting indoors and B1600 if shooting outdoors. A 13 ft. heavy duty lightstand and a medium softbox would give pleasant main light. Use your current flash as second light/fill on a light duty stand with swivel and umbrella holder. You can do a lot with this, and the monolight will have about ten times as much power. This would be a good basic studio type set up.
http://www.photoflex.com/Photoflex_Products/Constellation3/index.html
Would be the minimum amount of light you need for 2 light portrait use. Add bulbs and softbox and it just over your budget. 2 Camulet Genesus units would be the same cost of one light unit if you wanted strobes.
I use strobes, continous and natural light in my studio and sometimes all 3 at the same time. It all depend on the look you want. The strobes can do anything continous can if and I repeat If you learn how to use them and control the output. Light control is the problem most have with strobes. Continous has a lot more limits but is easy to visualize but controled totally different than strobes. Even a 200WS strobe would be at least 10 times the power of 2 continous lights used together.