Spoken Skills offers both pronunciation and speaking practice. You can listen, then record yourself repeating the passage and listen to yourself. I suggest that you try the sections Business English, Dialogues, or Speeches and Presentations.

Speak English is a British website that has words and phrases that you can listen to and repeat. Of course, everything will be spoken with a British accent on this site.

Talk English is an American website where you can listen to and repeat sentences on various topics.

Splendid Speaking is a website that helps people prepare for the IELTS language test, but they have many good resources and ideas for improving your speaking skills.

IELTS is an acronym for International English Language Testing System.

English Accent Coach is an interactive online game that will help improve your pronunciation. This website has been created by a Canadian professor at Brock University in Ontario. You have to sign up to use this website, but it's completely free. Highly recommended!

The American English Pronunciation pronuncian site is very good . You can listen to podcasts on pronunciation and practise some sounds. For example, here's a link to the podcast on the difference between "13" and "30".

Rachel's English has videos that help you see and hear how to make the sounds of English. There are lots of videos that you can watch and listen to.

Manythings.org is a website created by ESL teachers. There are some pronunciation practice activities here that you could try to see if you can hear the difference between some similar sounds. You might also find the Daily Pronunciation Practice section useful.

Please do not try the tongue twisters; they will not help your pronunciation at all.

English with Jennifer: Jennifer has a website as well as a YouTube channel with videos on many different language topics.