I do a quick analysis of every race at about midday and note my expectation on a spreadsheet. A side benefit of doing this that I hadn't thought of beforehand is that when I've had a losing race, I can read my comments for the next race. Even if my mind is steamed-up, at least I have analysis for the next race which was done with a clear-head. I can also see when there are several opportunities later in the day for swing trades etc. When I didn't do this pre-race analysis and I had a losing race, the time I had to make-up my loss was always the NEXT race! Sometimes I'd get lucky, but if the next race was a poor trading opportunity then I'd be much more likely to do daft things like doubling-up and going in-play.
After having a session where I went on tilt I always used to eventually come to terms with it and soldier on. Now what I try and do when I have a losing race despite my best trading endeavours is not beat myself up. I try and blank it from my mind in the same way I used to do with much bigger losses. Obviously I can do this much more quickly for these smaller losses! I then move on to the next race. It so often surprises me how quickly I can get most or all of the loss back. I then have a chance to make a little more. In the past I'd have no trading bank left to trade with!
After each race I note my P&L and make comments about the market. In combination with the screen video I record, this makes a useful review tool. I've thought long and hard about the pros and cons of constantly being aware of my P&L throughout the day and I've read many other traders' blogs about this. The danger is of course that when things aren't going well that focussing on the losses may make you trade worse.
On balance I find recording my P&L as I go along useful - for a start it's more up-to-date than my Betfair balance which may have unsettled markets to come into my account. It also enables me to have more perspective on the day than just a total P&L figure. After I've done my pre-race analysis I write a one-sentence forecast for the day - after all if there don't appear to be a lot of good trading opportunities ahead for the day, I shouldn't be beating myself up when I'm not making much money later on!