Is opposite side castling an advantage? I usually work things out as I go along. I don't know any openings and tend to improvise the opening and the middlegame.
For a player like me, is opposite castling a good or a bad choice? I took a look at the tactics involved in such a game (https://www.chess.com/forum/view/livechess/attack-on-opposite-side-castled-king) and it seems that you need a high tempo to perform well. For someone who never follows a strict plan and improvises, is this an advantage or a disadvantage? Should I castle on the same side and aim for a slower game with less pawn involvement?
Say, for example, my queenside is under attack and the opponent has castled kingside. Castling kingside would reduce pressure and allow me to recollect my thoughts. Castling queenside would allow me to put pressure on the opponent's kingside and form a counterattack quickly. For each of these possibilities, the play style must change, but does castling opposite the opponent actually give me any advantage apart from aggression? Possibly, it would allow my bishops to take a long diagonal against the opposing king, w/hile same-side castling would require more knight action.
The short answer is that castling long, vs. short or staying in the centre depends on the concrete nature of the position. I would advise against 'castling into it [an attack]', and give this quote from Pillsbury:


  Castle because you will or because you must, but not because you can


This means that if I gave a general answer of, say, 'always castle kingside, it's good', then that advice may not apply to many positions, and also goes against your player personality of working things out move-by-move.

If you could post some concrete positions into your question, then the community can comment on if/when castling queenside is appropriate.