Reliable updates... Considering I completely messed up my own schedule I think this is an appropriate topic.
One of the harder things about posting is being consistent.
That said, it is always good to have a selection of back up posts all set up to post automatically. I consider these 'fillers' because that is what they are doing. They fill in the gaps that might happen when life takes you away from the computer.
Another important thing is to not apologise every single time you miss an update. Updates get missed, this is life. How ever if you disappear for a few weeks or months... then you should do an update post with an apology and explain that there might be a change in the frequency of your posts.
For the most part people worry more about you then your posts. Sure a comic being left on a cliffhanger is going to garner a lot of interest and such. But once they realise that you might not be able to update for other reasons? People start to worry.
Also, if you are posting a series it can take a load off your shoulders to have a cushion of auto posts so you don't have to scramble to come up with something. Just saying.