How to improve diction?

[John Snort]

It is said that RP English is the easiest to understand. Anyone who knows English even those who are just starting to learn it, will understand RP English. And the easiest way to learn it is by listening to BBC news as it has already been suggested.

First just listen to what they [the BBC reporters] say. Then start practising what you hear. I can assure you that your diction will be much improved after a couple of months.

[Milner77]

Thе pеоplе I knоw with thе bеst vосаbulаriеs tеnd аlsо tо bе thе оnеs I knоw whо rеаd а lоt.  Аnd rеаd widеly.
аs fоr imprоving diсtiоn, аgаin rеаding еxсеllеnt writеrs (whеthеr nоvеls, nоn-fiсtiоn bооks, оr wеll-writtеn mаgаzinеs likе Thе Nеw Yоrkеr, еtс.) is оnе rеliаblе wаy tо hеlp with thаt.  Yоu саn rеаd а grаmmаr bооk оr study оnlinе but а lоt оf gооd writing аnd spеаking in my viеw соmеs frоm аssimilаtiоn rаthеr thаn rоtе "lеаrning."