Trading on horse racing
Pre-race is often the safest place to start trading horse racing. One tactic popular with beginners is swing trading, where you're going to be backing or laying a horse pre-race and making profit as the price fluctuates before the off. The aforementioned scenario of laying and backing a horse at odds of 2.0 and then 4.0 pre-race is an example of swing trading.
The tactic is to observe a horse racing market around 20 minutes before it's due to start. Open the price chart of a horse and see if there is a rough trend, is its price coming in or drifting out over time? Around 10-15 minutes before the off is when the market becomes more active and is a good time to place your opening bet.
If for example you have noticed a 'steamer', a horse that is being heavily backed in and its price coming down, back the horse with a small stake with the expectation of the price dropping further. This then provides you with a profit by laying at the lower price closer to the off.
Remember we are trading, not betting. The trick is to trade out when the trend is finished or when it fails to come to fruition. Staying in a trade in the hope that it will come back to you will hurt your bank sooner or later.
There's no exact science to swing trading and it will become easier with time. Consult these pro-trader's guides for both what causes swings in price and what markets to target, as well as a more specific guide on understanding the steamer in horse racing markets.