The most important aspect of lobstering is to stop, look and think. Lobsters generally won't bolt out of sight when you spot them, so the key is to not spook them Approach slowly, no rapid movements, and watch them for 'body language'. Consider their escape route and try to out-think them. If they have a great hole behind them, then the optimum thing to do is to tickle them from behind to get them to turn their tail away from the hole. If they have no hole to escape to, then it is easier, but what you want to do is direct their escape in such a way that it benefits you! Have your net ready but don't deploy it too early - lobsters have eyes and they can see the net! And remember, lobsters swim backwards, so position your net behind them and out of their sight while you occupy them from the front. Then, when you are positioned, give them a little scare and off they will fly into your waiting net!
A snare works well also, but you need to be in a position that allows you to slip that in behind them, and get them to lift their tail and step over the lower wire so that you can snare the body fully. You need to have the wire up at the top of the tail to really get them.
Finally, try to look for eggs first, and be gentle regardless. Hurting a lobster, ripping antenna off, or otherwise being abusive does no one well, especially if she is a female loaded with eggs for a future lobster season.
Have fun and good luck!