Writing a blog post for many can be a tormenting process, especially if you don't have passion for what you are blogging about. Having the ability to write a new post every day is a talent that is developed over time and is a habit forming process.
The best strategy to use when starting out is to just start writing whatever comes to mind. You don't have your topic decided upon when you start writing, rather allow yourself to go all over the place. What you end up with may constitute two or three different blog topics.
When you do get a solid topic, don't throw out the second or third topic. Set them aside and add to them as your thoughts come so that you can use them for the next day, or a different time that applies.
The important part is that you are getting your ideas on paper allowing you to continue on to a new thought without spending too much time focusing on the one at hand.
Many people think that you blog post has to be so specific for people to get value out of it, but it is more important that your topic develops a personal relationship with the people that are reading it. If they don't feel like they are getting to know you personally, they are not likely to come back for more reading in your blog.
Learning is a great way to have something to write about. I'm constantly learning from other entrepreneurs both online and offline. I absorb information all the time. The information that I take in is not specific to one person, but is formed over listening to the ideas of others which offers me the opportunity to relay a unique perspective to what someone else might say.
Get yourself out of your comfort zone on a daily basis and find new television shows to watch, new activities to do and even mix it up by socializing with different people. The more perspectives you receive the greater potential to say something interesting to others.