What do you want to use AI for? Writing dialogue? Programming help? Image creation?
If you are wanting to work in private on your own hardware, you'll need a GPU with a fair amount memory - less than 8GB makes it difficult/restricts what models you can run, 24GB (3090 or 4090) is much better and the peak of home usage. Nvidia is better supported than AMD but you can make the red team cards work with some patience.
There's also lots of various paid services that will give you working "in the cloud" AI instances to mess with. Typically costing 1-2$ an hour. These are cool if you don't have the right local hardware, but also a bit inconvenient. You can get much more powerful GPUs this way if you find speed of response is an issue.
For text generation for creating dialogue, the main tool to use at home is Oobabooga "text-generation-webui". You can also use it for "chatting", and in that case the Silly Tavern frontend has some useful additions.
This thread has a lot of info:
https://f95zone.to/threads/ai-uncensored-text-generation-via-oobabooga.162713/post-12221435
If you're looking at doing image creation, then at home "Stable diffusion" via the opensource project Automatic1111 is a good way to get started. Some users prefer ComfyUI which has a more "connect the function boxes" visual programming approach, kinda like Unreal Engine game dev.
Stable diffusion has a lot of constantly evolving parts, so recently I switched to use the "stability matrix" installer which helps with the install and maintenance.
There is a shared learning thread here:
https://f95zone.to/threads/stable-diffusion-prompt-sharing-and-learning-thread.146036/