It depends a lot on how it was stored, if fairly dry and warm, then I would remove plugs as well as changing water/oil etc etc, then put some diesel fuel in each cylinder, this will help to free off stuck rings, obviously leave overnight then spin over on the starter to pump it out the plug holes.
I would also change the fuel filter and the fuel before trying to start, injectors could well be sticky aftert this amount of time also, so may be very rich to start with, just see how it goes.
I work them up to fully hot in stages, running just a few mins to start with checking for leaks etc as you go, though I've never restarted a 18 year old unstarted engine, good luck, also use some iridium plugs as these will give a better spark so give you a better chance.
Some would say strip down first, with antifreeze being this old it will be useless and ther eis bound to be a lot of corrosion on the HG which may well blow straight away, your choice, I would strip personally but a lot depends on budget, ie if you can diy it ?
tabetha