I use european odds, hope you understand them from the example i'm giving.
For example, for tonight's final between Man Utd and Chelsea, their match odds at betfair (you can take another bookie of course):
Man Utd - 2.74
Draw - 3.15
Chelsea -3.1
All together gives a book of 100.5%
(of course you should take in consideration the commission they charge)
Say that for example, that there isn't any option for betting on the handicap 0.5.
So you can do this:
-get a calculator and see how much you need to bet on the option you want, i often use this one on the multiback option
http://www.arbcruncher.com/free_onli...calculator.asp
For a total stake of 100 units, and if i want to bet on manchester winning or drawing then:
53.48 units in manchester
46.52 units in the draw
Overall, that you'll give me 46.54 units of profit.
If i think chelsea can win or manage the draw, then the 100 units are distributed:
50.40 units at chelsea
49.6 units at the draw
Overall, a profit of 56.24 units.
If you think that this match will never end in a draw in the 90 minutes then back manchester and chelsea:
46.92 units in chelsea
53.08 units in manchester
Overall, profit of 45.44 units
In this case, at betfair you have also the option of betting in the handicap +0.5/-0.5, if you check the prices:
Manchester -0.5 is at 2.74 (same odds as the match odds for manchester to win)
And chelsea + 0.5 is at 1.57 (which is a better option that betting like i demonstrate above where overall backing chelsea and the draw only gives us an average odd of 1.5624 so backing chelsea +0.5 is better option in this case)