When you arrive at any dinner party make sure you arrive on time, and if possible with a small gift for your host as a thank you present. It's ok to be just a few minutes late but whatever you do, do not arrive early.
If you find that you are going to arrive too early then drive or walk around for a while, or go and get a cup of coffee or something, anything, but don't knock on that door or ring that bell early!
Why? Because it won't go down at all well with your host despite the fact that they will more than likely accept your apology for being early and tell you that it's O.K, it's not O.K.
What you would have just done is to throw a large spanner in the works for your host, causing major disruption to their preparations and timings.
This might quite likely mean that you never get asked back again. So don't arrive early!
When you arrive on time, enthusiastically greet your host and thank them for inviting you.
Wait for your host to introduce you to any of the other guests that may have arrived before you.
If your host doesn't do this, say hello to everyone and introduce yourself. A simple hello and your name along with a one sentence explanation of who you are in relation to your host is fine, with or without a handshake is acceptable. Obviously, if when you arrive you already know everyone anyway the greeting is far more informal.
Not everyone takes a thank you gift for their host, but it's always a nice thing to do. A gift of wine, flowers or chocolates are the usual sort of present.
When you give your gift don't make a big show of it in front of the other guests in case they didn't bring anything along themselves. This just avoids any embarrassment.
A word of caution: you need to be careful what you bring in relation to who your host is. For instance don't take flowers if you know your host suffers badly with hay fever.
In the same way you wouldn't take chocolates if you knew they were a diabetic. If you knew they were a wine buff it would be far better to take flowers or chocolates instead of trying to choose a bottle of wine they might like, but getting it wrong!
Don't forget you have brought the gift as a thank you for your host. So don't expect that bottle of bubbly you brought along to be opened on the night.
Whatever you do don't ask for your gift to be opened, or refer to the cost of it as this would be very rude.
Once you have handed over your thank you present simply forget it. Your host may or may not decide to open the gift you brought for all to share, but that is up to them to decide.
When you come to leave at the end of the evening, it's not really appropriate to take home anything you brought along as a present or gift regardless of whether or not it has been opened, even if other guests do it.
It's simply not appropriate. Even if your host suggests that you do take something home with you, don't! Just say something like, it was a present for them to enjoy and that you really wanted them to have it as a thank you.