It depends what specifically you're having trouble with. If you simply don't know how the word is pronounced, Google is always a good resource to listen to the pronunciation. You can also look in a dictionary to see the phonetic spelling (key to this is usually in the back of the dictionary, also available online with a search). If the issue is more you've heard the word and still can't mimic it, then it's probably a muscle training problem. Most people don't think of their mouths or tongues as something that needs training, but for learning pronunciation it's a must! I don't know, specifically what you are struggling with so here's some tips: Make sure for the "a" sound your tongue is flat on the bottom of your mouth and more forward in your mouth (just touching the back of your bottom row of teeth) Tighten up your mouth and don't open it very wide. (A US pronunciation would open the mouth wider) Also make sure the sound is coming more from your throat as opposed to the mouth. Here's a video I found you can try to mimic. https://www.youtube.com/watch?v=mhSMwZ2a1sw Hope that helps!

this is a good site with all of the sounds of English: http://www.antimoon.com/how/pronunc-soundsipa.htm

That's why we have IPA.

It is hard to talk about pronuciation using words.