You must have a white eraser that does not leave any marks on your paper. DO NOT USE the pink or any other colorful erasers. These colorful erasers are solely for school use not for drawing because they would leave marks on your illustration.
I use the Staedtler white eraser for my drawings. It does not leave any unpleasant mark or scratch.
Do you know how to clean a white eraser? Rub it on a table or a wall. It will get white and sparkling again. I discovered this technique at the graphic design school in Italy years ago.

The paper quality is extremely important. For drawing with watercolors and acrylics, it requires a type of paper that doesn't curl up when it gets moist. Same way for inking a comic or any other drawing that requires ink. For inking manga or other comics, it takes a smooth paper sheet that absorbs fast the ink and it doesn't curl or wrinkle up.
I like using Copic paper sheets, natural white, for manga. I bought it on Amazon for about $8.00
There are different brands of art paper. Make sure to choose one specific for manga so you'll know it's good for inking.

Caran d' Ache is my favorite brand for pencils colors.
I don’t know if here in the USA are popular like they are in Europe. Since 1915 this Swiss company has manufactured luxury and arts products. They have $10,000 ballpoint pens for sale on their website! Caran d'Ache trademarked the first mechanical pencil in 1929 and launched Prismalo watercolors pencils in 1931.
Regardless, you don't need a $10,000 pen, but the color pencils are definitely worth it. They have a wide range for the all art techniques from watercolors to wax oil pastels. Blick Art Material site has an excellent description and related videos of Caran d'Ache products.

In my opinion, Caran d'Ache is the best brand for color pencils. However, they are not economic. Start with a small size set and add more colors buying just a single pencil at the time. They are easy to find in art supplies stores and online on Amazon, Blick, and other related sites.

A couple of years ago I was looking to buy watercolors. Windsor & Newton or Caran d'Ache are excellent but not good for my thin wallet, so I checked several reviews on Amazon to figure out what brand I can get. I choose Koi watercolors. They are excellent for beginners and artists on a budget. Koi watercolors are affordable, and they have a nice variety of tones. I have to say I am amazed by their quality and price, definitely worth it.

If you draw manga, you know Copic markers. They are one of the best art supplies brand on the market and popular among mangaka. Copic is a line of markers manufactured in Japan by Too.The Sketch markers version has a chisel-style tip on one end and a brush style tip on the other. These two sided nibs are perfect to color small areas and give a brush effect to the illustration. All the Copic markers are refillable and the ink can be mixed to create custom colors. Their nibs a replaceable too. Copic markers have a vast variety of colors, and its ink absorbs nicely in the paper without leaves any wet marks.

You will need a good quality India black ink if you are still inking by hand your manga. Don’t use the cheap one! Cheap ink is too watery, leaves marks, and sometimes it looks almost brown. It’s not suitable for illustration and comics. I use Daler-Rowney® FW Artists' Acrylic Ink, India Black or Dr. Ph. Martin's - Bombay India Ink - Black. They are a good brand and the ink is a true black. I'd like to try the Deleter black ink. Their price range between $4.00 and $6.00, depend where you buy it.

Good quality paintbrushes can be expensive. The most expensive ones are made with real fur. I don't approve using animal fur for brushes or any other product, so I get the nylon hair tip. Their quality improved remarkably over the past few years. It's unnecessary to buy an expensive set of paintbrushes, get an inexpensive one or just a single paintbrush. It will do the job especially if you are a beginner. I don't have a particular brand to use. The primary thing is that the paintbrush has a good grip and the hair tip is soft and flexible.

These are my favorite art supplies that I use for drawing in particular Legends of the West. However, it doesn't mean you have to buy the same products that I like. Some artists have a particular pencil or paper that like to use, others don't have a specific brand.

For example, Mark Crilley underline in his Youtube videos that he doesn't make a great deal about the brand of pencil or watercolors that he uses.
I agree with him that it's not worth to invest a bunch of money for some art supplies, especially if you are a beginner. On the other hand, I think it's worthier to find what works best for you.

To sum up, spending a little on good quality ink, paper and colors pencils is a good investment. It's unnecessary to buy the top of the line or the most expensive one but you don't want to purchase inexpensive products either because, in the end, you will spend more money.

Experiment with various materials and brands and see what you like to use and fill more comfortable. After all, what really matters is improving your art skills and the most expensive tools won't help you in achieving that. It's not a pen that creates quality drawings, it's your hand.