For first periods, +.5 and U and -.5 and O are more correlated than dog and u and fave and over but those too are correlated - more so on big dogs/fave.
For soccer, if you bet every tie/under parlay you will make money. You will also make money on the dog/U and fave/O but tie/U is the best.
Almost all soccer ties are 0-0 or 1-1. Very very few are 2-2 or 3-3, etc.
Bodog and Instantaction sports used to take these. Killed them.