The best way to play for a draw as White is to stick to your main opening repertoire, only avoiding the sharpest lines where you are not sure of the latest analysis.
Playing an opening you know well prevents you from misshaps in the first phase of the game and arms you for the early middlegame. Moreover, if your repertoire is decent, it generally leads to equal or better positions for White, from where it will be easier for you to lead the game into dull waters (e.g. positions with symetrical pawn structures, mass exchanges, or forced lines leading to perpetual check).
A tactical line is not necessarily to be avoided. A common psychological trap is to avoid calculating any variation by fear of a calculation error, play passive moves, and drift surely and not-so-slowly into a lost position. If you stop yourself from using your capabilities (tactics, calculations), you diminish your own playing strength. Compared to a "normal" game, however, you can evaluate differently the positions reached in your calculations: even if you are slightly better, a perpetual is fine, a drawn endgame also.
Let's assume you are a 1.e4 player, for instance. If you go 1. c4 or 1.Nf3, you probably won't face any disaster in the opening, however after move 10 you will find yourself in unknown territory, in an equalish-but-with-a-lot-of-play-left position and with a lot of decisions ahead to make by yourself. Moreover, exchanges don't come for free in positional lines, if you aim for them you will often trade your good pieces and keep the worst ones.
On the other end, if you play your usual 1.e4, you can use your knowledge to navigate through the opening without huge mistakes and it is your opponent's job to make something special happen and create chances for himself.
He will probably refrain from the French for fear of the exchange varaition, or from 1...e5 because White can aim for liveless positions in, say, the 4 knights or the exchange Ruy Lopez. In case of a Caro-Kann, your usual line is probably not very risky for White, but you can also go for a Panov: isolani positions can get very sharp when White plays for an attack, but Black cannot do much to avoid simplifications if you simply play for d4-d5 and exchanges.
Against rarer stuff like Pirc, Scandinavian or Alekhine, your usual repertoire probably yield a small plus for White. If you go for it, you will be in a good position to force simplifications later in the game.
The tougher nut to crack, or rather to tame, of course, would be the fiery Sicilian. There you have a choice: if you are confident in your theoretical knowledge, you can prepare your opponent's usual main variation having in mind that all the equal-and-simple lines and all the perpetuals are okay for you. That makes White's preparation much easier actually. Or you could go for something solid like the c3-sicilian, where (as in the Panov) some games can get wild but that is merely when White goes for an attack. In your play in the center and look for simplifications, you will very often get them.
Don't change your very first moves, but adapt your play to your goal only when you start calculating lines at the end of the opening and in the early middlegame. Don't forget that it is much easier to force a draw from a slightly better position than from a slighty worse one.