Have the installation checked and fully serviced by a reputable engineer - preferably someone you already trust but this is probably hardest to achieve, look to find someone by word of mouth is the nearest you may get.
Make sure the blower for the engine room works AND you get into the habit of using it 5mins before startup,5mins after shutdown - make sure your service battery can cope with this!
Fit (or have fitted) an up-to-date non-halon auto extinguisher with a manual override "yes I know dear, the boat is on fire but the auto extinguisher >will< kick in in just a moment or two"...
See if you can get a look at the tank space to check if the tanks are OK - normally VERY difficult but you can try.