I haven't tailored anything recently so can't recommend you anything in good faith.
This is a
good post that you can consider referring to.
With regards to stylistic choices and colours... For your first and only suit you want to make something that is as versatile as possible. Navy and mid grey are popular choices for business wear because they do not stand out. I would make a strong case for brown as a versatile casual colour as well. This means you'll be able to wear the same outfit over and over again and people wouldn't bat eyelid. Compare this with a crazy check pattern and people would notice when you wear it again.
The same applies to stylistic choices. Tailor a double breast jacket and people would notice. Not so much a navy single breast jacket. Would anyone without sartorial inclinations notice a peak lapel? That's debatable.
The next question you should ask yourself is if you really need to tailor a suit. At the price point you're willing to pay you won't get fantastic quality ot even service simply because there aren't enough margins built in for it. It seems like you don't know what you want either which increases the likelihood you will waste a lot of time and effort try to make your ideal suit but failing at being able to communicate and control the tailor effectively. This means even with all the research in the world you may still end up with something you don't quite like but can't put a finger on.
If you have the luxury of time I would recommend looking through the selections and buying from
Spier Mackay they arent the best but they fit your budget and turn out a better quality product than any tailor can do in Singapore at the same price point. Invest in a measuring tape, get all your measurements, and spend the next few days browsing through their suits before buying. Thereafter visit a good alterations tailor like Meng Yee and alter to fit. I guarantee that you will be much happier with the end product as compared to visiting a tailor.