what you want to get is some larson soff boxes ... or strips
the old ones sell on eboink from time to time, they are worth their weight in GOLD
larson has sales every week ( get on their email list ) sometimes buy one get the 2nd FREE ..
the thing is any diffusion / modifier eats light, sometimes a stop, sometimes more or less.
umbrellas are OK but depending on what skin is on the umbrella it can be contrasty or not enough
boxes give nice soft faux north light ... and larsons last forever.
i have a few old ( like 30 year old ) larson boxes and a chimera ... the chimera is junk by comparison
if you have hot lights, be careful, a lot of boxes can't take the heat, so you might be stuck with using
umbrellas whether you want to or not ...
If you are doing portraits every week, bite the bullet and save up for strobes. If they are at the studio, then super light and portable is not a big concern
Older less glamorous set ups, by current day standard can be found, and are entirely workable. I waited and watched, and found what I feel was a deal. I bought a Speedotron 2400w pack, with three heads and a flight case for the heads, three caps, three 7" reflectors, and 2-11" reflectors for $1200. The down side of this rig is the pack is heavy. Smaller more portable ones are available. The stuff is built to last though. I later bought three used soft boxes ( 12x18, 24x30 and 36x48 ) with compatible speed rings for $300. Wescott. Good brand, lightly used.
If you are doing portraits, a lot of the time the look you are likely to want will vary from wide open to more serious amounts of depth of field. Sometimes I think you might be hinting at the 'new' photo florescent lamps.
Continuous lights will have you working wide open all of the time. Use strobes unless you are doing video as well. Video guys in it seriously usually hate hot lights as well, and have good CRI rated multi-tube floros that have a look of a soft box. Co-Flos is the industry term I believe.
Umbrellas have a nice look, but the light goes everywhere.
Soft boxes make great key (main) lights and smaller ones or strip lights - a longer and skinner soft box make nice hair/accent lights.
Fill light is fine with an umbrella. Usually a background light can be direct, but sometimes a shoot though diffusing white umbrella works well also.
High key shots can be pulled off with umbrellas.
I am not trying to scare you off. I started with hot lights, and stuck with them for a few years.
Then I moved to rigs with a bunch of hot shoe flashes on stands with umbrellas. Better than hot lights, but this was pre-radio sync, and the cords and batteries (pre NiMh) were a hassle as well. This is where I learned that umbrellas spilled everywhere, unless you spend all day hanging flags from the bunch of extra and tall light stands that you don't have at this stage of the game.
The heat of hot lights was not compatible with a nice sitting experience, and is even hard on still life stuff. The new cfl continuous source ones I don't see putting out enough lumens to cut it for portraits, but may work for product stuff,where shutter speeds can be stretched , and the LED ones are not quite bright enough yet, particularly when sometimes you are aiming for a point source effect.
Yes with my advice I was thinking strobes.
At this time, it is the cost. I do not stay a lot of time indoors. Still spend more time outdoors. So it is used less often.
I have hot and cold lights...plus LED's..
I prefer flash - I have several studio monoblocks I've bought for $100 or less each, and mostly bounce them (or shoot through) white umbrellas.
Really nice light for not much money..
In a small studio reflective umbrellas are hard to work with. It's tricky to control the light. But it can be done, and they have a great character.
If the studio is small you will end up with your key light source(s) close to your subject.
You don't usually want to light the model and the background with the same light. (Looks crap in most situations.) So you put the light close to the model and place the model as far away from the wall as possible. This way the light lost most of its energy once it reaches the wall, this goes quick! If you put the light further away the model and background will be more evenly lit.
You can also create some angle with the key sources, this will put more contrast in on the models, you can control this with a second umbrella on the other side, but this is two lights already. Than you can always add a different light for the backgrond.
In a small studio you will enjoy the softbox most since you want to reduce spilling. If you have to light bigger spaces go for the umbrella or more lights. But hey their characters are a lot different so this is just the easy way not the only one.
The main problem with softboxes is their size - get them far away enough to light a figure and they become more like a point-light source.
I often "build" a softbox with a strip of translucent fabric draped over a boom, and sometimes will mask the sides with black duvatyne or felt. Sometimes I end up with a Box made from three or four c-stands. For low-key stuff, I really like a 6' high strip light, maybe a foot or two wide. Panel systems can be really helpful for these kinds of setups.
If your room is small and you're using umbrellas, get a few yards of wide black felt (it's lightweight and cheap). It goes a long way in helping you control all the dang light bouncing around the room when you need a little more contrast or drama. Cover a problem wall with it using blue painter's tape - super handy, and you can cut down problem windows with it, too.
In this shot, you can see the "strip light" reflected in her shades. A Speedo head behind a strip of diffusion, maybe 6' high by 12" with 2' of black duvatyne on each side, sewn by a sewing-grandma-lady (find 'em at the fabric store, ladies who make draperies and curtains can make photo scrims in their sleep) , and a grid head on the background.