The world of lighting does not start and end with softboxes, you can have a lot of fun without them, until you become sure of what you want to achive from your portraits. .
As you will have realised, we are all going to tell you different things, as each person has a different style and different equipment. There is no definitive way.
My take on this, as you are just starting and on a budget is to get a 2nd flash, a couple of cheapish lightstands and adaptors to attach the flash to them and some radio triggers.
You can at this early stage get away without a softbox - you can add that later when you know more about what you want.
Alternatives to softboxes to get a large soft lightspread - bounce light off a pale wall or door, shoot through a piece of white fabric or a bit of shower cutain, a piece of tracing paper, bounce off a white or silver reflector, use a bit of crumpled and then straightened out kitchen foil to bounce the light from. Use a bit of foam core or a sheet of cardboard painted white or silver or covered in kitchen foil.
Photographers have used scrims and silks for years. Also look into gobos.
People also forget the glories of hard light in portraits. Make a cardboard snoot to put over your flashgun to narrow the beam rather than widen it. Remember that you can also control flash beam width by choosing the angle setting for your flashgun (settings will be equated to lens length on the gun - 34mm, 50mm etc). Look at some of the interesting hard light portraits from film noir style or seach film noir on Google Images
https://uk.pinterest.com/narmstrong711/film-noir/
Placeing objects, bits of card cut into shapes, twigs from the garden, between your subject and the light cast enticing shadows and emphasise different aspects of the face or body.
Look up some of the old black and white hollywood film star images to see how object shadows were used for emphasis.
Check out
Robert Harrington on B and H photo youtube channel, he has several videos on using small flash. People sometimes make grids/honeycombs for small flash by cutting bunches of drinking straws down and tying or gluing them together then taping them in front of the flash with gaffer tape or some other means.
The '40s Glamour Portrait (I hate the final post processing, but the lighting is good info)
View: https://www.youtube.com/watch?v=TPBO9paDGmA
Bringing Your Portraits to Another Level with Grids
View: https://www.youtube.com/watch?v=OIZMcm6ZRFY
Hope you have lots of fun!