Basically you can divide studio equipment in different categories :
- The light heads /generators
- Light diffusion and reflecting
- Light Stands, backgrounds and holding accessories
Be aware that studio equipment can become quickly expensive and bulky.
The minimum requirement is 2 flashes and tripods, and two umbrellas, but I would recommend to begin with a (big) softbox instead of one umbrella. 3 flashes allows much more possibilities.
You must choose as well between 3 main categories of flashes :
- Compact heads (enough for most people)
- Separate heads and generators (more powerful and expensive)
- Battery powered flashes (useful if you plan to set your studio outside, for portraits or wedding jobs).
More infos about what you plan to do would be helpful. You should as well have an idea about the brands available in your country, you may need some service. A brand well distributed with a good reputation is an important consideration.