I have 2 years worth of preseason lines and can tell you from betting the preseason and following it closely since 2004, that in the NBA preseason, a general rule of thumb is to:
1) take the underdog
2) take the team that you feel has absolutely no business winning the game
Examples that are winners so far in 2006 are a plenty:
Toronto on 10/9, 6-point dog at 5dimes, 4-point dog at Olympic, won outright over Washington
Philly wins outright over Phoenix as a 6.5 point dog
Boston, a dog, buries Cleveland
New Orleans, a dog, beats Dallas outright
Memphis, a dog, beats Houston outright
Detroit, a dog, buries Miami
Atlanta, who stinks and was a dog, beats Memphis
Minnesota, who probably should not be favored over Milwaukee, was favored and covered
Washington, a dog, covers against Chicago
I pick every game during the preseason and am 10-4 so far, and I only bet 1 game and am 1-0, but haven't posted anything yet, so maybe it's about time to start posting my picks and bets (although I don't make hardly any bets during the preseason unless I see good info about a coach playing starters extended minutes, etc)...
Sac +4.5 at Dallas
Sea +3.5 at LAL
I like Sacramento tonight...Their first preseason game and their new coach seems amped to get things going...He said he is not going to play all 18 guys on the roster or even 15...He told all his starters they'll be playing 20-something minutes and it sounds like he would like to win this game...Dallas didn't play Nowitzki, Terry, Harris or Stackhouse in their preseason opener (Harris and Stackhouse are hurt) and it sounds like those 4 may not play again tonight...Dallas didn't practice on Wednesday due to "too many aches and pains" according to Avery Johnson, so I like Sacramento tonight enough to bet them small...
Seattle is back-to-back tonight, but LAL doesn't have Phil Jackson and Kobe didn't play their opener, but they still beat Utah by 15, so I have no opinion here but will pick the Lakers simply because Seattle is playing their second game in 2 nights...
There are informational databases out there for those people who like to back check systems...
Here are 2 samples to a NBA database I created:
I have all the lines and results going back to the 1991-92 season...