As a general rule, players have favored serves.
And one important consideration you should always have when receiving is to figure out what they are as soon as possible and physically compensate by moving over and covering these serves.
You figure out these favored serves by simply keeping track of which way your opponent is hurting you the most. Then you move over to cover and become determined to not be caught reaching on them.
On the contrary, you want to hurt your opponent on these serves and force her/him to serve to the less-favored side.
You move until you are being hurt equally on both sides. You will also find that your opponent will tend to miss more serves when trying to hit to the less-favored sides.
There are plenty of examples. Pete Sampras favored hitting his second serves up the tee in the backhand court. If an opponent didn't move over to close this up, he got aced quite a lot.
Most lefty's are especially adept at spinning the ball wide in the backhand court. When receiving serve against them it is sometimes necessary to move over and return from a position partially in the alley in order to force them to serve more down the middle.
They may get you occasionally with this serve but they will miss it more often.
On the other hand, if you allow them to hurt you with the wide serve they can do this all day with few errors.
The trick for the lefty who wants to hurt you with this wide serve is to get good enough hitting up the tee to threaten you and hold you in a more neutral position. Then, on the big point, he/she can hurt you with the high-percentage wide serve to the backhand.
One other way of figuring out what your opponent's "money" serve is on the ad side is to notice where your opponent hits his/her first serve the first time it is ad out. Usually they will go for the serve they like best. Keep this in the back of your mind for later.
They will try to obscure this by moving their serves around, but when it gets to a crucial point late in the set, watch out for the one they like.