Let’s start off by just looking at this Wikipedia article, and appreciate from a cautious distance the variety of input methods there are:
As a beginner language learner who may or may not have a deep interest in a linguistic appreciation of the Chinese language, I will simplify the choice to the most practical considerations.
In China, Singapore, Malaysia, they use Simplified Chinese characters in their education system.
In Taiwan and Hong Kong, they use Traditional Chinese characters.
Not all of the characters are different, but a significant number of them are. You can choose based on why you are learning Chinese (e.g. if you think you are likely to live or work in Taiwan or Hong Kong, rather than China in the future for instance, learning to read and write in Traditional Chinese would make more sense.)
If you ask me (a Singaporean who learnt Simplified Chinese in school) for my recommendation, I personally think in the age of digital communication, when we are typing with the assistance of computers/phones more so than writing, it frankly doesn’t matter as much. As someone more used to Simplified Chinese, I can still recognize most Traditional Chinese characters when I go to Hong Kong or Taiwan, because they still bear resemblance to the Simplified versions. This, however, as I suggested in class, is not an opinion that is necessarily shared by other native Chinese speakers or other Chinese language instructors you might encounter. I have friends tell me they can only read in one of the two, while others find the differences manageable with some Googling. As you can see on the resources page, there are plenty of resources for converting Simplified to Traditional and vice versa, so unless you foresee a future in which you will need to write Chinese by hand a lot, I don’t think it really matters which you choose to learn.
As for typing in Chinese, there are many different ways to do this, but there are two primary ways here that you can explore – Pinyin/拼音 (pīn yīn) and Bopomofo, or the Zhuyin input system / 注音符号 (Zhù yīn fú hào). The latter is used in Taiwan, and would demand more familiarity with tonal marks. This article explains it well:
Bopomofo: Using Zhuyin Input on a Taiwanese Keyboard
It is also possible to change your language/keyboard settings/preferences on your computer so that you can type using the Simplified Chinese (China) keyboard, but have it render everything into Traditional Chinese. You can even opt to use the handwriting function at the start in order to improve your writing. While I expect most beginning learners of Chinese to pick Simplified Chinese, I think knowing what your options are, and considering them early on in your journey to learn a language is important.
To explore different options for setting up a Traditional Chinese keyboard: https://www.pinyinjoe.com/windows-10/windows-10-traditional-chinese-pinyin-input-setup.htm