http://www.tennislive.net/
good for scores and previous matchups and stats
livescorehunter.com lots of live feeds for matches
flashscore.com
good scores and you can click all your betting and put it on mygames to make it easy to see who you bet on
espn3.com carries a lot of the matches on the aussy open.
Remember if you are new to tennis betting Shari has a good article in the tennis section, will probably have to search for it.
My tips
Don't look at rankings. They mean about as much as someone typing in caps.
Its early in the season so be careful of people like to retire.
Know your books policy on retirements. I play at betislands and they have a one serve. So if you bet big your guy serves and quits as mardy fish did on me last year, you lose your bet. Some books retirements are refunds.
Look at surfaces, Just because someone has won their last 4 matches doesn't mean he will do well on another surface.
Big favorites get beat all the time, but don't bet a 5000 line just because its their.
Best of luck to all