Helpful Resources for Speaking

Stress, Rhythm & Intonation (Youtube Videos)
Stress and Rhythm Practice (Highly Recommented)
Vowel Changes in Stressed and Unstressed Syllables (Highly Recommended)
Intonation Practice (Recommented)
Articulatory Setting: Why Facial Expressions Matter for Pronunciation? (Recommented)

Stress, Rhythm & Intonation (Articles)
Intonation and Stress in English
Sound Scripting (Stressing Practice with Native Speaker Example)

Accent Comparison Practice
Try reading/recording the following script yourself first and compare to the following MP3 files:
"Please call Stella.  Ask her to bring these things with her from the store:  Six spoons of fresh snow peas, five thick slabs of blue cheese, and maybe a snack for her brother Bob.  We also need a small plastic snake and a big toy frog for the kids.  She can scoop these things into three red bags, and we will go meet her Wednesday at the train station."

New York Accent MP3 with Script
Chinese (Mandarin) Accent MP3 with Script

Note: For more variety of accent samples for other speakers, go to The Speech Accent Archive

Commonly Mispronunced Consonants and Vowels (Youtube Videos)
/v/ vs /w/ (e.g. vine vs. wine)
/l/ vs /r/ (e.g. lice vs. rice)
'th' /θ/ & /ð/ vs. /s/ & /z/ (e.g. sink vs. think, breathe vs. breeze)
Diphthongs (gliding vowels such as [aɪ̯], [aʊ̯], [eɪ̯], [oʊ̯])
/æ/ vs /e/ (e.g. bad vs. bed)
Long 'e' vs. short 'i' (e.g. leave vs. live)