What camera do you have right now, a mirrorless or DSLR? naah, I am consider myself as an amateur as well. You can always check many threads here for those wanted to trying out what photography is. But most discussion posted few years back, but the ilmu shared are still there. Welcome to the photography hobby.

Just with any craft, the more you practice, the better you are. If you want to improve fast, take 5~10 photos everyday and try to analyze how can you do better in each shots in term of composition and lighting. Get honest opinions from people around you to see if they like your photos.
Then you can find on youtube or other social media those who are good in these genre of photography. Try to study and understands, what makes their photo good. Try not to focus on too many genre at the same time. Start with the one you like the most first.
1. Be invisible by using a small camera and small lens. 2. Get a lens with longer focal length so you can have a comfortable distance with your subject.
3. You just have to push yourself to do it. The more you do, the natural you will be at it. Unless you are super obvious, most people don't think you're taking photos of them. They will also worry to make a scene if they confronted you yet you were only taking picture of some one or some thing else next to them and embarrassed themselves.
Business  card? Seriously ? That is so old fashion. You should show them your ig account explaining that you post strangers photos on your ig so that they can be famous too.   

Get a lens with longer focal length

200mm max focal will be too obvious to others when you wanted to take street photography, try to get any short focal length kalau ada. Unless taking pics from a distance should be okay.

Getting new perspective from shooting the same thing is one of the best way to improve your vision as a photographer. If you composition is so so in one place, it will be the same every other places you are going to shoot. If you can impressed people around you (who are also very familiar with the place) with photos you've taken at the same place from a different perspective, then that's the sign of progress.
80-200 is good for stealthy approach, but generally such a long focal length is not suitable for street. Street photography need to show not only the people, but the context. So showcase of background is important also. If you only shoot like a sniper with 80-200, your photos will get boring very soon. Eventually, you need a focal length about 23mm-35mm for your 40d and mastered up your courage to do close up shot of strangers if street photography is your thing.
    @TS, Nothing wrong to learn with trial and errors. Bumpy ride, true, but if you have the passion to back it up, it could be also an very enjoyable ride as well to discover thing for yourself. That will also determine how passionate/determine you are in this craft. Some times, when it was handed to you, you may not appreciate it as much as something you found by digging around. But luckily, we are leaving in a digital age where you can get most of the info you need from youtube university. You can also look up Manny Ortiz on youtube, he also learned everything he knew from youtube.
this. 
TS, you should go visit W_9235 post at the showcase section. He spoke from experience. You will be inspired by seeing the journey of his growth from a newbie photographer to a pro photographer.  https://forum.lowyat.net/topic/1207851

Everyone has been giving really good advice, especially on learning and improving your skills...

...so let's talk gear. 

1. I think based on your description, a good next lens will be the 18-135mm STM. It's a good all rounder, plenty sharp and goes for around RM600+- used.. For around the same price, the wider angle 10-18mm STM is also fabulous for the price... check kldslr's used list. The great thing about the genres you mentioned, I don't think you need wide apertures.... yet. hehehe... of course, this is just based on your posts which shows you have a tight budget. I was using that 18-135mm for a looooong time and it served me well for many purposes.... before.... aih... the inevitable buying

In fact, I will find a reliable camera store in KL that allows you to trade in your lens (won't be much... but who knows) to further cut down your lens trade in price. If you still long for a telephoto later on, the 55-250mm STM ain't that expensive AND is also damn bargain+sharper than your current lens if you're not desperate for wide aperture lenses.

2. I think then, the next simple purchase for your genre would be a nice tripod. Many china brands now make 'decent' tripods with good load bearing as long as it's not those huge telephoto lenses. for a simple setup like 40D+18-135mm lens, many tripods will suffice. Just double check if the tripod head and mount is NOT plastic. I think for <RM200 you could get a simple tripod with very basic metal ball head + arca swiss style plates.

3. The trick about talking about gear is to resist getting too deep into GAS territory. I always feel having the right gear or sufficient gear helps a lot, but like architectural photography for instance... if you start talking about TS-E lenses, tall tripods, etc.. it can really end up being an expensive hobby.

Cheers mate, and look forward to your photography journey~