My advice, if you want to become a good conversationalist, is just to crank up the amount of time you spend having conversations.

I can think of three people I know for whom that does not work. Not because they do not think they have opportunities for conversations, not even because they have opportunities but do not take advantage of them, but because they do, and put a great deal of effort into it, and yet I can see that it is not working for them. They are getting little in return for their efforts, because they are all doing it wrong, each in their own way. Whatever they need to be doing instead, having more conversations isn't it.

Advice is good if it works for the person it is addressed to. It is bad if it does not. General advice like "talk to people more" cannot be expected to generally work any more than an appendectomy will work for every case of abdominal pain. An appendectomy will work only for someone whose problem is a diseased appendix.