There are plenty of low tech ways to improve the heat and hot water use in your home before getting onto how to improve boiler efficiency. Without going into details here, the first thing any homeowner should think about is home insulation and air tightening. Local environment departments should be able to help you out, and tell you how to get a home environmental audit.
The next thing to think about in the home is how you use your heating and hot water. If you do not control the heating zones in your house, the most cost effective thing you can do is invest in programmable thermostats.
Other simple things you can do before getting to the home heating boilers include making sure you have not obstructed the radiators with drapes and furniture, put reflectors behind older radiators, and bleed the air from each radiator in the system at least twice during the heating season.
So what about the home heating boiler itself. Some have user maintenance schedules - things a non-skilled person is encouraged to do - do these. Also stick to the maintenance schedule that is laid down and call in a professional on a regular basis. Get them to do a tune up for maximum efficiency.