Regular maintanance I do myself. Oil, tire rotations, filters, plugs, brake pads, all pretty simple stuff.
I suggest getting the repair manual specific to your car and see if there is a forum for your car. (I drive an SRT-4 and my wife a Taurus - there are great message boards with tons of info for both.)
For more involved work, I have a trusted mechanic that I have been using for 20 years.
Try to find a good local guy. Ask friends and family where they go and if they trust their mechanic, then use him.
Dealer for me would be last resort. Way too expensive AND I generally do not trust the work they do, but that is just me.
Bluesman