There is no time limit in the game, and, as far as we can tell, the age of your character doesn't make any difference.
Similarly, it doesn't really matter if you're good or evil. Completing a quest in one way, or choosing one quest over another, won't affect what happens in the rest of the game.
You can hold at most nine resurrection phials in the game. If you pick up a "tenth" one, your character will simply drop it. So if you find that you don't die much, sell excess phials so that you don't waste them.
Barbers and tattooists act just like regular shopkeepers, but when you "buy" a style card from them, they'll perform the indicated operation on you rather than sell you the card. Every style card you have in your possession will be available from each barber and tattooist that you visit.
Escort quests are the most difficult quests because it's sometimes difficult to keep characters from being targeted and attacked. To make these quests a little easier, spend some experience on the "heal life" spell. Casting the spell will regenerate the health of you and your nearby allies.
Your combat multiplier affects how much experience you gain in the game -- including when you drink "ages of" potions. So try to get your multiplier to at least 10 before drinking such potions.
When you load a "hero save," your character information will be from the time of the save, but the world information will be from the last "world save" (including auto saves). You can use this feature to pick up multiple copies of objects, including things like silver keys. That is, you can start a quest, pick up an object, "hero save" your game, load the game, and then repeat.
Even if you're planning to rely on melee or ranged attacks, it's useful to learn the "lightning" and "slow time" spells.
If you're playing The Lost Chapters, don't spend all of your general experience in the "strength" or "skill" areas. If you do, you'll max out the skills in the areas and end up with experience that you can't use.