Short answer:
Use the Oxford Dictionaries‘ pronunciation guide. Select “English (UK)” if you want to sound more British, and “English (US)” for the American version. Keep your Singaporean accent, but develop a new one if you need to.
Long answer:
I’m an English Literature graduate, and I entered NUS with a very, very heavy Singaporean accent. I can speak Singlish like any other normal Singaporean, but after some years of suffering and recording my own voice, my students are surprised when I make the switch from my teaching voice to my “for taxi driver uncle” (Singaporean/Singlish) voice.
<If you wanna hear what I sound like these days, check out my music, but just read on if you wanna, no loss — Take Your Time (Bedroom Demo). Warning: no autotune.>
I still remember the day I decided I really had to work on my pronunciation. I was making some clever-clever point about something or other being an anachronism, clever-clever except for the fact that I was saying “AN-na-KRO-niz-m” instead of “a-NAK-ruh-niz-m”.
My hitherto strait-laced lecturer almost giggled as he corrected me.
So began the painful process to correct my pronunciation, bit by bit. I still have some Singaporean-isms in my speech — some of my “L’s” and vowels aren’t properly enunciated, for example. But by and large, most of the problems are gone.
The quickest way I’ve found that works is to record yourself speaking — or in my case, singing. My 2011 recordings really exposed how much work I had left to do, and how difficult that work is. Singaporeans/Asians, try saying the word “golden” now. Do you notice how much it sounds like “gowden”? Or this fantastic one — “children”. (Chewren, hee hee..) Try your best to properly pronounce the “L” sound. It’s not easy, I know.
To this day, I use online dictionary apps to make sure that I’m pronouncing my words properly. It’s an ongoing process.
It’s also important to pay attention to word stress, which is the emphasis that we place on certain syllables within a word. The dictionary.com pronunciation guide is a good way to understand this in a visual manner. The entry for the word “decide” shows us this guide: [dih-sahyd]. If you stretch the second syllable [dih-saaaaahyd], notice that it doesn’t sound as awkward as stretching the first syllable [diiiiih-sahyd].
One benefit I’ve found is that no English-speaking foreigner has ever found it hard to understand what I say, no matter how quickly I’m speaking. And it’s true — when you switch to Singlish, the ang mohs really tiah boh (the foreigners really don’t understand), especially if they haven’t spent any time in Singapore/Asia before.
There’s also the matter of sentence stress, which essentially is the choice of what words we choose to emphasize in a sentence. This has some impact on how our listeners perceive our meaning and intention when we say something.
For example:
Put your phone away. (Instead of putting it on the table, in your pocket, etc)
Put your phone away. (Instead of your pen, or toothbrush, etc)
Put your phone away. (Instead of my phone, or his phone, etc.)
Combining proper word stress, pronunciation, and sentence stress will help the average Singaporean become more intelligible to an English speaker who has no knowledge of Singlish or the Singaporean accent.
Funny story:
I actually tested my different accents in Copenhagen. When a friend and I conversed in our Singaporean accent, our Danish friend assumed that we were speaking in a foreign language that was only slightly related to the English language. And when we switched to Singlish (“Eh, you eat oredi anot?”), she thought it was Chinese.
Edit:
I’m still terribly proud of my Singaporean accent, and of Singlish in general. If you live in Singapore, you NEED it. If you’re a Singaporean overseas, it will be THE thing that unites you with other Singaporeans living overseas. That and char kway teow.
‘Ang moh tiah boh lah’. I learned this in a Malaysian movie. Lol.