Let your tech know if your guitar has any special "issues." Does it rattle or buzz on a certain string at a certain fret? Are the electronics acting funny? Maybe only once in a while? Is it slipping out of tune? Are you breaking strings?

Your guitar guy is good, but he's human and can sometimes miss things. If there is something specific that you would like addressed, point it out when you drop it off. It's MUCH easier to work on the electronics of your Strat while the strings are still OFF!

Another thing to mention is if you play in a non-standard tuning. You may play a half step down (or MORE!), but your tech may not realize this or maybe think that your guitar is just "horribly out of tune." Things like this matter greatly to the effective setup of your guitar, so mention it! Your tech might even have some helpful suggestions, such as changing string gauges!

Speaking of helpful suggestions- maybe you think your guitar is already all that it can be and there is really nothing that can be done about its dull sound, or tuning issues or noisy pickups or ... well, you get the idea.

Ask your tech for a suggestion! Most guitar techs love the instrument as much (or MORE!) than you do, and will be happy to suggest alternatives and solutions to your troubles in a variety of affordable options! For instance, lackluster tone can be eliminated by changing pickups- an operation that can range from an affordable $50- to several hundred... and that's just for the parts!

Changing pickups can be dramatic and sexy, but maybe you almost like the sound that you have, but it's just too dull? For just a few bucks your guitar guy can swap out some lesser electronic components, like pots or caps, and brighten a dull guitar, or tone down a harsh one.

Here are a few other basics to consider:
Do you like the action where it is? Really?
Do you actually USE that whammy bar?
What style of music do you play?
What sound are you shooting for?

Finally, the thing to keep in mind is that the "search for the ultimate tone," is an ongoing, never ending quest. Working WITH your tech and his experience may not make the road to Tone Heaven any shorter, but it can make it smoother and more understandable.