I think the biggest challenge is talking about something interesting on a regular basis. If you harp on the same things all the time people will become turned off and stop following you.
The one vlogger I follow has something that others aren't doing and that is the key. His vlog is normally on a Monday and it coincides with an information list that is released on Mondays.
In order to be successful you need to find something similar that will be unique to your vlog. You need to be entertaining and different. If you don't have a personality then rather skip the idea.
Loads of users try it and are embarrassingly bad. I take my hat off to them for trying but they won't be successful.Whatever they blog about is normally old news so it has no interest to anyone what so ever.
If you are considering using this as a source of income start out slowly with one vlog a week ,but find content that makes you stand out and be entertaining.