Every blog needs a foundation. Platforms provide that foundation and a framework on which to build your blog. They are what you attach both the internal workings and the public exterior. There are a number of platforms, but only some are worth considering in a very informal and conversational style.
In addition, you don’t need to be an expert on your topic in order to have a successful blog. For example, readers of a cooking blog don’t want to read a textbook from a food scientist, they want to hear the experiences of someone who has actually cooked some real meals, mistakes and all.
To be successful as a blogger there is really just one requirement: a passion for your topic.
At its heart, blogging is about sharing your knowledge with the world. Choosing a topic that you are passionate about makes the process of starting a successful blog so much easier. Writing about more than one topic is totally fine too. As long as you are writing about things that you are genuinely interested in, your passion will shine through and keep your readers interested.