A blocked nose is often caused by irritation from dry air, smoke, or dust. Removing these irritants would help tremendously. A dehumidifier can make a big difference as well.
Constantly runny noses however are caused usually by allergies. Some allergies are seasonal, whilst in countries like Singapore, where the weather is pretty constant, the problems tend to be perennial. You should seek treatment for this.
If untreated an allergy may result in secondary problems such as ear infections.