I have always wondered about Betfair trading as it appeals to my personality to place my bets, close them and not worry about who does or doesn't win the race.
I have tried it a few times, but like most people I ultimately fail when I stuff up and a big loss comes along.

The last few weeks have been slow for my normal systems with too many races washed out and the other selections just breaking even.
I decided to use this time to give BF trading another go.

One of the issues for me engaging in BF trading has been the lack of real information about what bet sizes should be, what kind of target to aspire to etc... There are lots of people having their two cents on the subject but rarely do you come across anything really useful.

And then I came across a post in some forum in a land far, far away and the guy stated, clearly, what he considered your bets would need to be to meet a profit of $2,500 per month.
Assuming one tick betting he described how one might aspire to having a bank of $1200 with $50 bet sizes and aim for a target, generally speaking, of $100 a day. He was suggesting betting on 30 races a day. He was allowing for blowing your entire bet on 5 races.

This was the sort of info I wanted...

I decided to start with $5 bets, the minimum, as I didn't want to waste money if it didn't work out.
This meant I wanted to make a profit of 30 cents per race, for 30 races per day, at least.

I started a week ago and so far I have won every day, winning around 90% of all races I bet on, and I am just under the overall target for the week.
The only times I have lost have been when I am not sticking to my own rules and not paying attention.
If I feel myself getting a bit cocky or distracted I get up and leave the next few races until I am hungry to give it a go again.

I feel I am getting the hang of it and will try to increase the bet size each week based on bank. I have seen in a few places people mentioning that once you get to a bank of around $2,000 it becomes harder to trade as you don't have your bets matched as easily.
I think I would be happy to sit on bet sizes of $50 if I get there. A few grand a month extra would be fine by me :-)

Now I want to give those who are curious some info into what I am doing, some observations I have made and some suggestions for anyone wanting to try this.

Tools - you need the right tools. I have never used the right tools before. It has changed things for me.

Tool number 1 - you need some trading software. I use Bet Trader and I am happy with it. Its fast enough, the ladder is a nice visual and I have a good feel for it now. I would suggest anyone trying these forms of software, read ALL the instructions and look for videos on youtube on how to use it.

Tool number 2 - you need a tool that shows you all the fixed prices for all major bookies/tabs at a glance. I was recently introduced to dynamic odds and it is brilliant for what I want. Make sure you set your prices tool up so price changes are easy to discern - like colour coded.

Tool number 3 - if you can afford it, use two laptops or computers or two screens. It is a lot easier if some of the information is on one screen and the rest on another. It just saves you those crucial milliseconds.

Tool number 4 - READ as much as you can on the subject. If you want to trade, look at youtube vids on trading and scalping. Even though a lot of the info is repeated, you can't read too much on other peoples experiences.

Technique - there are many different ways of trading. Some people engage in one tick trading, others in two tick or more, its up to you. I would strongly recommend you use the tick offset tool in your software set to the ticks you want, with hedging. I believe it takes a profit for me faster than I could, at times. It also allows you to fire in many bets at once if need be and I couldn't hedge them as fast as the software.
I chose one tick betting as I wanted to minimise risk.

Entry price - the crucial part of trading is the entry price. Set it wrong and you watch your money go away. During my week of watching most races on BF and looking at its interaction with the fixed prices with bookies there are a number of entry price techniques that are obvious.
For example... there have been a number of races I have looked at where a few minutes out the BF price suddenly heads north and leaves the fixed price on all books far behind. Today I saw a race where it did this. The price with all books was around $3.50 but BF suddenly took off and went up to $5.00. It stayed in that range until a few seconds before the jump and then it plunged down to meet the true price. This occurs in quite a few races.
Similarly, I have noticed it is not uncommon for the BF price to go down under the highest fixed price on books, thereby creating a strong arbing opportunity. It surprises me that these price variations occur when so many people use bots these days.

If you set up your tool for looking at fixed bookie prices and compare these to the BF range of prices in front of you, you should be able to select a reasonable entry point. I have found that the weight of money indicator in the Bet trader software does not correlate to the direction of the next traded bets. The strongest correlation is between the top fixed prices and BF.

When things go wrong.
Do things go wrong? Sure. Don't panic. I don't use a stop loss option, but I do kill a bet sometimes to limit the damage. Even though I believe I understand what is going on price wise, BF does sometimes just take off and go the wrong way against all logic. Usually it comes back to earth but I have been left with a few bets on the wrong side.
What can you do? You can take a loss, and limit it to a dollar or two before the race starts.
Or, if you know a lot about the race and the style of racing, and you feel confident, let the race go live in play and set your price so you can get out as soon as possible.
I try not to go live in play. It is one of my rules to avoid this if possible.

Here are my rules...
1 - stop trading with one minute to go. Sometimes you get caught, but I won't start a new bet in that last minute.
2 - don't go in play. Again, sometimes you get stuck with it, but try to cash out before it happens.
3 - if the horse is paying less than $2 I back it. If the horse is paying more than $2 I lay it. Why? Sometimes you will get stuck with a bet not matched. Statistically a horse below $2 is going to win more often than it loses. (there is a boundary between $1.80 and $2.00 where I may not obey this rule religiously)
4 - have a break regularly. Every ten races I get up and have a walk around, do something else for ten minutes or so. It doesn't matter if you miss a few races.
5 - have a goal but don't worship it - let it guide your actions.

My final rule - be realistic. If you are betting $5 per bet, then a reasonable profit from the race would be somewhere in the 15 -30 cents range. Its not much, but if you win more bets than you lose, your bank will grow, your bet sizes will grow and you will win more.

It is really a game of patience and a slow, accumulating grind through which you will learn every day.

I hope that helps someone.
I will report back in a few weeks to see if I have fallen off the rails :-)