A couple of things about sourdough starter

The basis for good sourdough is a good, happy, healthy starter. How do you do manage that? 

Name it.  I find that attaching a name to inanimate objects attaches me to them.  It is easier to me to care about something with a name.  My starter is affectionately name Gertrude ( and you can get some Gertrude here if you want).

You have to feed it regularly. I always discard some (save it in a jar to use in other recipes) and then feed with equal amounts of flour and water. I never measure how much starter is in there when I feed it, but I like to make sure that there is at least as much flour/water going in the jar as what is left (usually, I am adding more). 

Some recipes call for a specific poolish or levain. This will give specific measurements of how much starter, water, and flour to add. When making a recipe like this, I always mix it in a separate jar and save some of my original starter in its jar.  

If I am not going to be using my starter for a few days, or a couple of weeks, I feed it and put it in the fridge. Over time it might have a greyish liquid start to collect in it, called hooch. It is a natural alcohol that your starter produces, and it just tells you that it is hungry. You can stir it in the next time you feed or pour it off (this is what I do) and then feed as usual. 

I have had periods when I go out of town for longer than a couple of weeks or know I can't handle feeding it and don't want to see it in my fridge, so I have dried it out. Spread it on some parchment and let it air dry over a couple of days. Break it up into pieces and store it in a jar in a cool, dry place. Once you are ready to use it again, rehydrate it with water, and then basically, you feed as usual.  

I killed my starter. What do I do?

Sourdough starter is hard to kill, like SO hard to kill. People get a little freaked out when they see the hooch on top (but hey, the grey stuff is delicious… well, it is sour, but don't be scared of it) and think they killed it. It isn't dead unless you see actual mold; you haven't killed it. It might need a few days of being out of the fridge and regular feeding to get it happy and active again, but it is not dead.  

If you got rid of the starter you thought was dead, you could ask a friend for some more, or you can make yourself some more again. I sell my dried-out starter here as well. 

My starter smells like acetone? Is this normal?

Sourdough starters have a variety of smells that come with them, and it having a bit of an acetone smell is normal and means it is probably hungry!

I've been feeding for days, and it won't grow or pass the float test. What do I do?
Keep going!! Try feeding twice a day for a few days and see if that gets things going. Or change out your water source. The water you are using might have something in it that kills your natural yeast.  

A few other things that can (not always) hinder activity in your starter:

If you are using metal utensils, you can try to stick to something metal-free.  

Is it really cold where it is being stored? That can slow the whole process down.

Is the flour you are feeding with really old? The fresher, the better, also make sure it is unbleached.  

Some tips:

You can have a starter made from basically any flour, but consistency is key. Try to use the same kind of flour to feed your starter. If you have a sluggish starter, sometimes a feeding that includes a little bit of rye flour in the mix (or whole wheat) can help get things going. But of course, there are always exceptions to the rule.  

Speaking of your starter being sluggish, sometimes, to speed up the amount of time it takes for my starter to get to peak activity so that I can use it quicker, I place my fed starter in warm water. Make sure it isn't hot, but just warm. I sometimes switch the water out to keep it in a warm bath.