Obviously being IC (in character) is one of the key rules to follow in this game, and for the most part it's easy enough to tell the difference between what is IC and what is OOC (out of character.)
There have been previous posts of advice on this, so I will not go into it in absolute detail - check Ben's post here --> http://forums.darkgrimoire.com/viewtopic.php?f=20&t=2340 for the basics. A much-missed player, here called Carlo, also once made a post on the topic that I would link, but it seems to have been eaten by a forum upgrade at some point.
This post is about common sense, and to clear up a few things.
1. I do not expect you to only talk about items that one can find in-game. For example, as there is cider present in inns, it is a logical assumption to assume that somewhere in Valorn we have at least one apple tree (probably not many though, as the cider has been notoriously difficult to track down at times.) I would not consider it OOC to talk about apples.
2. One thing that has always been, and remains OOC, is roleplaying that you have a musical instrument when you do not have an actual in-game instrument equipped. There is a discussion in the Q&A forum in which I outline the reasons for this, if you are interested. I do not however see a problem roleplaying that you are reading a journal, for example, if you do not actually have one equipped.
3. Common sense is a dangerous thing to invoke, as people have varying levels of this attribute. To take an example, following on with the fruit example, know where to draw the line. If you are sitting peeling lychees in the inn, you are going to be warned for it. When making your assumptions about what can be found in-game, please remember the setting. Valorn is not an advanced place to live, as after the fall of the Golden Age there were generations who lived with absolutely nothing. It is only recently that they have managed to rebuild their civilization. Apples and korungas might be viable fruits, but hothousing lychees and pomegranates is probably not something that any crop-grower is concerned with. Likewise coffee and chocolate do not exist within the game. The climate is moderate; quite cold in Winter and fairly mild in Summer, so all of this puts technology / exoticism right out of the picture. If you are in doubt about something, play it safe. Here are some examples to illustrate the case.
a. *Jennifer Bumblethwaite tucks a white rose behind her ear* <-- absolutely IC, as there are roses mentioned in game.
b. *Jennifer Bumblethwaite tucks an orchid behind her ear* <-- rather OOC, and certainly risking a warning. Orchids are not something that would naturally occur in the lands of Trinald.
c. *Jennifer Bumblethwaite tucks a pretty white and pink flower behind her ear* <-- an elegant and IC solution to the risk of giving a real-life name to something. Here the item is described for the benefit of others in the room, giving an instant visual image, and avoids the sticky possibility of a warning from a passing constable or god.
I emphasize that this is not meant to serve as a killer to your creativity, and if you receive a warning we are not acting as policemen but rather as the guardians of the brilliant roleplay that makes this game so special. There are people out there who have proved that they cannot use common sense in their roleplay. One famous example of this from way back when I started in this game as your average novice roleplayer, quite a few years ago, were the people who enjoyed hanging from the non-existent rafters of Dundee Inn. We have had our phase of drawing the line at not allowing anything that isn't mentioned by name in-game and that does make life difficult for those roleplaying well. The problem about this rule is that drawing a line is very difficult for moderators as well as players. If people are abusing this, or I get a flood of 'I got warned for talking about sushi in game!' emails, then we may well just have to go back to drawing the hard, basic bottom line.
Thank you for reading this, and for making the effort to be creative but at the same time, appropriate.