I have a 1990 30G, same boat except better looking (30T has ruined lines just so you won't bump your head in the forward cabin).
Engine: Replace fuel filters at least every other year....manual says 250 hours, I do 200 max (been burned on this). Change oil every year regardless of use, no more than 100 hours. Yanmar 2gm20f consumes oil, always check it and keep it topped off. Inspect mixing elbow every 200 hours; you'll read a lot about this part in these forums. Don't let it go, it will halt you quick. If the engine runs dirty or smokes (grey, not blue, white is steam--check raw water intake and/or impeller), first cause is mixing elbow, second is injectors. It is good to have them pulled and rebuilt every few years. Run engine at least 85% of wide open throttle, I cruise at 2900-3000 rpm to keep things clean. If you are racing and not motoring much, take the boat out every so often and run at wide open throttle for about 30 minutes. Diesels hate light loads and low rpms.
Use an additive in the fuel to prevent mold/mildew. Fuel polishing is expensive...I cut an inspection port in my fuel tank when I first obtained the boat, drained the fuel into jerry cans, and cleaned the tank until white rags came out spotless. Replaced the fuel using a diesel funnel filter (West Marine), never had problems since. Diesel = clean, clean, clean fuel! It doesn't hurt to replace fuel lines every ten years or so.
Sail the boat flat to go fast. Add a rigid boom vang (Garhauer is best) with a control line to the helm, and learn to use it in combination with the traveler. Modify the traveler control lines so they are easily accessible to the helm as well (I moved the cam cleats to the cabin edge and lengthened the control lines) If you keep the sail flat and drop it down on the traveler, you can go fast with full sails after others reef. With full battens you can keep the jib in tight and backwind the main a little ("fisherman's reef") before having to put in an actual reef. Downwind vang and traveler will enable you to stretch the main so you can drop the boom down further without fouling in the spreaders. This boat is designed with the mains'l as the engine and a small jib to channel air over the large main, not a large Genoa for power like masthead rigs use.
I worried about the iron keep a lot for the first few years, and even ground it down and epoxied. Then my yard mentioned it would take over 10,000 years for it to corrode away....at each haul out there often a crack somewhere at the hull keel line, especially in the front. Hunter says open it with a Dremel, let it dry out, and fill with 5200. If it is really bad, glass over with a strip of cloth and epoxy (West Systems), paint and don't worry about it anymore. The bottom of the keel will always be rusty, learn about "rust converter" used on freighters, treat, paint, splash.
Hope this helps, have fun!