This is very good advice on how to speak fluently:
https://youtu.be/tq_ad-CqBik

It's true for preparation, but the real key to fluency is speaking in a non-structured environment. That goes for Esperanto just as much as any other language, or any skill for that matter. It's only in a situation where you have to think and communicate on-the-spot, again and again, that you attain 'fluency'.

The word 'fluency' is so often abused. It means that the speaking (or writing) has an easy flow, where you aren't racking your brains to come up with fluid sentences and you aren't pausing unnaturally before replies. Mastering a language isn't easy, so people seem to want to keep lowering the bar for what they deem to be fluency.

I look at it this way: a person can read and prepare for learning to swim as much as they want to; but until you get into the water and actually swim, you're not swimming.

Easiest way to achieve fluency, if you can't attend an international congress is to have a conversation in Esperanto with another Esperantist about something that is personally significant for you or related to some communicative need.

Fluency comes from linking situations to sentences.

You will achieve fluency much more quickly this way than practising dry textbook sentences like 'the cat on the mat is playing with my pen's aunt'.

In days of yore there were plenty of Esperanto clubs where you could practise. These local Esperanto clubs hardly exist anymore, but you do have Skype now, and there are many more international meetings of Esperantists.