If you play a stealthy character, be extra vigilant when checking large open areas for your quest target(on assassination/kill missions), as your sneaking may well mean the target remains hidden in some dark corner unaware of your presence while you pass right by.
Believe me nothing is more aggravating than the experience I just had spending 5hrs working through a dungeon thoroughly exploring every nook and cranny, spending 6days in there and gaining 4 levels in the process, only to eventually give up on any hope of finding my target (I thought he must be behind that underwater door guarded by 5 dreughs) and slog back to the beginning feeling defeated. Then
in the room that contained the entrance/exit I walst through without sneaking, as I presume everything was dead, and who should come charging out of some dark corner at me but the DB traitor...
Or are there alternatives?
You can either bash the door in with your weapon, which is illegal and will draw the city guards, or you can use an open spell to unlock it.
Also does your skill only go up when you succeed? Like if I try to pick a whole bunch of locks but fail, will that improve my rating there at all?
Your skill goes up with every attempt, succeed or fail, but you only get one attempt on each door.