When to place bet on trifecta and when to place on each way

[Offline]

Hi all punter, need to get opinion from all you buddy on the topic mention above. When do you normally place a eachway bet in a race and when is the best time to place a trifecta to get good return.

I have tried once during year 2000 Melbourne Cup where I place 30 dollars on trifecta and I won 1700+ for 1/2 unit from Vic TAB. I roll 1 of my favourite (which I think will get a place and normally is not a favourite horse in the race)with 5 other horses (normally favourite with 2 medium odds and 2 outsider). I think this give me a good value bet. I did the same for last years Mel 2001 but just miss out on the second horse. Two of my pick came out 4th and 5th. A little bit off. Need your advice...

[The Catparrot]

If you want to bet each way you do it with a bookie in fields of eight horses on short priced favourites that you think are value.
The longer the odds of the horse, the poorer value an each way bet is.
Similarly the bigger the field the worse value an each way bet is getting one quarter odds for the place.

With trifectas you must beat the market. There are no hard and fast rules but if there are short priced horses in the race I'm only interested if I think the short priced horse has a good chance of missing the place.
I don't have hard and fast rules - but I like to avoid favourites. If you base your trifectas around favourites you must lose on the tote.