Bit of both to be honest.
Most characters I make tend to have some guidelines but they are not set in stone, all of them share a few common themes such as I hate/try to avoid destroying robots as I dont like old technology being destroyed.
At least one playthrough I'd do will be using guides (after Ive done the game a few times without) so for any tricky quests I can see the outcome e.g. In F3 Ive always struggled getting the 'Ghouls move into Tenpenny and kill everyone a few days later' ending. Same with the wedding sub quest in Rivet City, had to look up that one to get it to happen, though when it did I nuked everyone at the ceremony so that was kind of mean.
Fast Travel (or not) is an interesting argument - I agree with someones comment re F3 vs FNV - F3 its pleasurable to travel on foot, FNV dull and this is entirely due to not having random encounters and wandering enemies. Probably little FT to start with then more depending on the playthrough.