Short handicapping lesson

[fjh513]

New member and a relative newcomer to horseracing...

With the season just around the corner here in NJ, I need to revamp my handicapping "skills" and sure could use help. I haven't had much luck in the past. My bets are mostly exacta / tri boxes, and I also enjoy playing rolling pick 3's,with one race being a single to keep the costs manageable.
I would like to ask you guys /girls how you narrow the field when looking over a race. How do you toss out the non-contenders ?
Is there a quick "system" you use that makes you focus on horses you like in that race ? something that can be done in the time between races ?
I appreciate you help and good luck with your picks.