First, you need to decide your target audience that can be conservative, liberal or moderate. After deciding your target audience, you should start writing on political issues that attract people towards your blog.
You can easily find many free platforms on the internet like Blogger and WordPress where you can write blogs without paying even a single cent. However, it is highly recommended that you start a political blog on your own website.
If you want to start your own website for a political blog then you need to register a unique domain name first. You can find many decent website hosts that provide everything from domain name registration to website templates. Pick one that suits your budget and simply design your political blog the way you want. Then start writing whatever you like about politics and the best part is that no one can copy or publish your posts anywhere else as it is illegal.
You should also decide the purpose of your political blog. Whether you want to start a blog as a hobby or you really want to deliver a message to the masses.
Always allow comments below your blog post which will help your readers give some feedback after reading your blog. It will help you in interacting with many people and make further improvements in your blog.
If you become successful in getting a considerable number of visitors to your page on a daily basis, then chances are quite high that you will start attracting many advertisers as well. Most will pay you by displaying their ads on your political blog.
The most important aspect of starting up and making a new blog successful is the quality of your write ups. If you write top class content, it will have more readers as compared to a poorly written political blog.