I have set rules that I subconciously enforce upon myself.
Set battle style: It prepares me for the Battle Frontier and online play
Battle animations on: It doesn't bother me if they are off, as long as there is a log like on Shoddy. But if the arent on, and there is no log, it makes me feel like I missed something crucial.
Text Speed: Fast. Like most people over the age of 7, I can read faster than I speak, therefore text that scrolls along slowly drives me MAD
Pokemon: Anything but the fire starter. I love all the fire starters. Especially Blaziken (Ruby was my first pokemon game, and Torchic was my starter) and Infernape. But I have a natural dislike of the norm. EVERYONE picks the fire starter, so I dont. I usually go with the water starter because they tend to be bulky. The Grass starter has to be a steaming cup of badass for me to pick it. Like Sceptile, even though his level up move-pool sucked.
I then catch the 'Bird' pokemon because there is always a forest to go through, so there are always bug and grass pokemon, and I didn't pick the fire guy, so it would be hell without a flying move.
I then use Serebii to decide which early pokemon learns all the useless HMs (Bidoof = yes).
I then go randomly, usually aiming for a wide range of types. Electric, Fire, Fighting, Poison, and all that jazz. I catch most of my guys early, as I your pokemon should always be stronger than the wildies, and I dispize having to train one pokemon only, just so it can 'catch up'. But at least 1 Steel type or future steel type (like Prinplup, Scyther, and Pineco) is required.
I don't care about natures/EVs/IVs because I don't have the resources that early in the game to manipulate them easily. I don't care about that until the after-game. I refrain from trading, because, like previously stated, I feel like they are cheating with their boosted exp.
Items: I guard my berries vehemently. If its one-use only, Im never going to use it unless I can buy more. I use Healing items in Gyms only, and I will get halfway to the next city, and turn around to dash back to the Pokemon Center because Im too cheap to use my potions.
I never use the Itemfinder/radar and Usually my pokemon have the items that boost their STAB, like Charcoal on Houndour.
And ya. I have literally flinched away from the screen when a Platinum Walkthrough popped up, because I was halfway through it. NO SPOILERS! And when a new gen comes out, I try to keep up to date until they announce the release date, and then when I find out that, I mark it on my calendar and close myself off from the rest of the pokemon world, as not to spoil the story line.