Dont be daunted
a preventive maintenance service to an outboard , ( assuming it is running OK to start with ) is pretty straightforward
New plugs - doddle
New fuel filter-doddle
Change of gearbox oil-doddle
Lubricate with fresh grease the obvious grease nipple points around steering / saddle etc - doddle ( especially if you replace with new grease nipples )
Power trim ? Check top up level
Many other simple things can be done which one day could prevent a baffling breakdown ,
Clean fuel tank out ( not with water ! ) add fresh fuel.-doddle
Clean spark plug leads / ignition pack and lightly spray with WD to protect- simple
Look over all fuel hose / bulb / connections for sign of rubber cracking and possible failure - outboards hate air in fuel line-simple
Look over wiring for signs of obvious corrosion on connections , if necessary disconnect spade / bullet connections wire brush clean , reconnect and lightly grease-simple
Look for poor / weak / worn wiring connections as these can cause a dead engine.
( Easier to check this over on land than at anchor at sea trying to find out where the electrical fault is and why engine wont start like I do ! )
eg : disconnecting / cleaning battery connections retighten- simple
Check starter motor connections tight , clean & very lightly grease starter gear making sure it all operates freely-simple
All of the above of course takes time which is what you are paying for, but isnt that difficult , you may find you have no choice with the age of your engine but to DIY ,as you will find a lot of service chaps wont touch older engines.
Slightly more involved would be replacing water pump impellor , but even this is straightforward with basic tools.( The problems you may come across here are on older engines where bolts have corroded in and wont budge , thats when the fun starts ! )
Doing all of the above should give more reliability to your engine ( I'll just add my legal disclaimer bit here as I am no expert just self tought )
Did I mention I can do great deals on drysuits , lifejackets ....blah blah blah....