What kind of music do you make? Are you interested in making beats more than creating synth sounds...or are you up for a bit of general over all tips and tricks, how about mixing tips?
The choice is yours ;)
If you're new to synthesis then I'd recommend taking a look at the ES2 and Sculpture tutorials. If you like sampling and creating beats then you can't get much better than Ultrabeat, and if you want dozens and dozens of more advanced tips then check out the Logic 303 TNT.
Also, it might be worth choosing a preset bundle or creating your own bundle as there are discounts included:
I'd also really recommend the Logic 202: Logic's Plug-Ins: Unplugged. Bear in mind this one was made with Logic 7 - so the plug-ins may look a little different aesthetically, but basically it will all work the same in Logic 8.