Many players serve without any type of routine. They just go to the table, decide what serve to do, and then serve. If all you want to do is get the ball in play, that's fine. But if you want to serve effectively, there's more to it. (Before we go on, here's a Tip on Practicing Serves the Productive Way, one on Ten Steps to a Great Service Game, and one on Purpose of the Serve.)
First, you need to mentally prepare yourself for each serve. That means going through a pre-serve routine. It can be short and simple, such as just coming to a complete stop (as required by the serving rules), where you finalize what serve you will do, and then clear your mind to prepare for the upcoming rally. Or it could be a bit more. Some bounce the ball on the table or even the floor. Others wipe their hand on the table. I like to push up the sleeve of my serving shoulder, drop my serving arm so it hangs loosely, and then swing it back and forth one time like a pendulum (which also helps loosen the arm muscles). Then I come to a complete stop, visualize the serve, and then serve it. (I decide what the serve will be before I start this routine, though I often change my mind afterwards while visualizing the serve.)
Second, you need to visualize the serve. That means all aspects of it:
Does this mean going through a checklist of all of the above? NO!!! It means visualizing all aspects of the serve, taken as a whole. You can recognize a person's face without consciously noticing what makes it different from another's. Similarly, you can visualize an entire serve without consciously noting each aspect. (Here's a Tip that covers much of this - A Journey of Nine Feet Begins at Contact.)
Third, you have to be ready for the follow-up. This means getting into a proper ready stance immediately after the serve. It also means mentally being ready to follow up the serve. This has to be a flexible approach - never force something that isn't there. For example, you might decide you are looking to follow your serve with a forehand loop. If the opponent pushes and you are able to get to it, you get the shot. But if your opponent attacks the serve, drops it short, or catches you off guard with an aggressive push that you can't get your forehand on, you need to flexibly react to that shot. Similarly, a player may decide he's going to follow with a loop from either side, depending on where the ball goes - but if the opponent drops the ball short, you have to flexibly change your shot.
This last aspect takes experience to get right. For example, if an opponent pushes your serve back over and over, an experienced player may decide to use the following tactic: when he serves backspin, he'll likely get a heavier, lower return, and so follow with forehand or backhand loop, depending on where the ball goes. But if he serves no-spin, he'll likely get a lighter, higher return, and so look to follow with a forehand. (I do this tactic all the time.) In theory, this makes it look like you should serve more no-spin, but there's also a higher probability that it'll be attacked, plus you need to vary the serve so the opponent can't get used to one serve, so you have to vary between backspin and no-spin. (Here's a Tip on Serving No-spin.)
So consider taking a 1-2-3 approach to serving: mentally prepare yourself, visualize the serve, and prepare for the follow-up.