I forgot to answer the question.
I have about $200 split between two wallets currently. I try to add a little at a time then sometimes I'll use a little for a purchase and try to make sure to never spend more than 1/2 of what I have. For example about a month ago I had close to $250 and gave my wife $100 for her birthday so she could shop a little bit wherever she wanted.

A couple other suggestions:
1. always pay bills electronically then you never have to stop to pay a bill and if someone ever says you didn't pay the bill you ask your bank to research it and let them fight it for you.
2. always carry some tools in your truck so you don't have to pay someone else to put in that battery. even a simple adjustable wrench is sufficient to change a battery. You don't have to spend a lot, just don't buy cheap chinese made tools. Stop by sears right after a holiday and go straight to the clearance table and pick up a set of decent tools for cheap. usually they will discontinue sets or have some in fancy packaging specifically for that holiday that they will put on clearance and you buy it and toss the packaging and have several good tools for a good price. A basic adjustable wrench is a start, then add some screwdrivers and a small set of wrenches then a socket set, usually 3/8" drive will do most autmotive work. Then maybe a 1/4" drive socket set and maybe a 1/2" drive long bar and a couple big sockets, one that fits the lug nust because they have less chance of slipping off than the cheaply made factory lug wrench.