While it is clearly obvious, that internet can't replace a decent teacher, you still can find tools there to make your learning process more effective. By the end of March 2017 hundreds of websites related to the subject of learning Chinese language can be easily googled. Some of them are entertaining (more or less), others focus on grammar, characters or vocabulary. How not to get lost? Here is the list of Chinese language learning tools that I find quite helpful.
ChineseConverter is an ultimate web-based tool for both Mandarin and Cantonese learners. It can literally help you to convert everything you may ever need to convert, e.g. Chinese text to pictures, numbers to Chinese numbers, Traditional Characters to Simplified, Characters to Pinyin, Zhuyin (Bopomofo) or Jyutping. It also allows you to look up animated stroke order for multiple characters at the same time on one page and to create Chinese character practise writing sheets customised to your needs. All free of charge.
Another website that allows you to create various worksheets is ArchChinese, which in order to provide support for Chinese language teachers who are working at K-12 schools and universities. The website doesn't only feature teaching tools (worksheets, game makers, vocabulary list generator etc), but it can be a great source of information for you to plan your studies, such as radical tables, lists of frequently used Characters, some grammar explanations etc. Right, it was made by teachers for teachers, but if you are the one who is teaching you, check it out. Membership fee applies, but some of the features are available without signing in.
PurpleCulture offers a selection of tools very similar to #1 and #2, but it is still worth mentioning at least for the dictionary&sample sentences part. This is a Hong Kong based online business dedicated to providing Chinese cultural and educational products, so don't forget to check out there selection of Chinese learning books on sale.
Chinese boost is a promising blog on how to learn Chinese created by London-based Chinese language teachers. I am sure that beginner learners will find the blog part very helpful, but frankly speaking I love it for it's grammar boost section.
HanziDB is an ultimate Chinese character database where among other things you should check out character lists for all six levels of HSK exam (HSK stands for Hànyǔ Shuǐpíng Kǎoshì; 汉语水平考试)... well, you know, just to make sure that you are staying on the right track.