Most people wear their signet ring on their non-leading hand. In other words if you are right handed (which is the majority of the worlds population) you would most normally wear it on your left hand. Left handed people generally prefer to wear their signet ring on their right hand.
Traditionally people always wore their signet on their little “pinkie” finger. This is because you can then use it as a seal without actually taking off the ring. When creating a wax seal (to seal a letter, for example) it is best to slightly roll the ring to create a deep clear impression in the sealing wax. It is possibly more difficult to create a seal if you wear the ring on any other finger and that is why the tradition developed to wear your signet on the little finger.
If you wear a wedding ring this is normally worn on the non-leading hand. This means that a signet ring worn on the little finger then touches and rubs against the wedding ring. In this instance, if you find this annoying, you may prefer to wear the signet ring on your other hand – your leading hand.
Ultimately there are no strict ‘rules of etiquette’ regarding wearing of a signet ring. It is a very personal thing and in our opinion you should always wear your ring however you want!
More recently, (particularly in the United States of America) it is quite normal to wear a signet ring on another finger; possibly your ring finger or middle finger. Bear in mind that in this instance the ring needs to be larger to keep it in proportion to the size of the finger.
In aristocratic and upper middle class British circles it was uncustomary for men to wear a wedding ring but this tradition is slowly in decline. In these circles, quite typically we find that a signet ring is an accepted alternative to a wedding ring.