Really as for a tune up there is very little to do on the china engines. You can remove the head and make sure there is no carbon on top of the cylinder and inside the head. If there is it is cleanable with a wire brush and carb cleaner then reinstall the head with a new gasket and torque the bolts in a cross wise manner to 100 inch pounds. If it has acorn nuts that bolt the head on I replace them with regular 6x1 metric nuts as the acorn nuts have a tendency to bottom out and not really tighten the head down. Yow can also make sure the head is true (not warped) by flattening it with some medium grit sand paper on a piece of glass. And a good quality new plug never hurts LOL...
You can also increase some performance by porting and polishing the intake and exhaust in the manner described in this thread:
There are also some high performance ignition CDIs available like the one from J&N Motors
that allow you to tailor the ignition to your riding habits and increase performance.
As for the fuel line if you have the stock clear tubing throw it away and get some 3/16" neoprene fuel line at Auto Zone and a couple of good screw clamps.
Good luck getting a bike shop to even touch the bike though as long as it has a motor on it...
If you have any problems there are lots of good folk here with a lot of knowledge they are happy to share or PM me and I will help if I can.