For any pokémon in Sinnoh I throw a Fast Ball first. For legendaries I then weaken it, throw Ultra Balls (Around 20) or Dusk Balls (Same numbers, if in a cave or at night), then alternate around every 10 between Ultra / Dusk and Timer Balls.
If I have a pokémon with a sleep move i normally only weaken to about 1/2 hp then put the wild pokémon to sleep. I've been doing this in LeafGreen with Butterfree (and normally do it with Bulbasaur if I chose that as a starter - at lv. 70 Venusaur will still have Sleep Powder and Leech Seed xD), or paralyzing with Pikachu if Butterfree isn't an option.
Or if I have a pokémon that's a lot weaker than mine, doesn't matter if its lv. 40 and its only weak because I'm using lv. 80s from my last HeartGold / Platinum saves, its Quick Ball then Nest Balls all the way.
I've only just kicked the habit of holding down AB when the ball opens up to the end of that turn on Gen III, and alternating between that and going A when it opens, B, L+R when it closes (All held down) from Gen IV. Obviously I knew they did nothing, but it was just a habit.