How do individuals on this world efficiently identify potential mates?
For an "efficient" identification there ought to be some outward difference between sexes. This difference might not lie within the human sensorium (for example, a difference in body smell that humans can't pick up, a different skin color that only shows in ultraviolet or infrared and so on).
Anatomical differences could be enough to either be easily spotted (sexual dimorphism, or simply noticeable bulges in different places) or lead to different behaviours, not necessarily "squealing". Skin color, hair pattern, bone structure.
All these could be even unnoticeable one by one or to the untrained eye, but immediately obvious to your aliens (akin as how humans can be trained to sex pullets from cockerels by eye, but they don't know how they do it - it becomes obvious to them).
Fashion is another possibility. If the difficulty you noted was also awkward for them, they'd probably evolve means to circumvent it and make mate selection more efficient again. In some Earth cultures, specific items of apparel were reserved to indicate social status, marital status, or even sexual availability - fans, sashes, garlands, shoes ("And now you've gay bracelets and bright feathers three! / "Yes: that's how we dress when we're ruined," said she -- Thomas Hardy, The ruined maid)
Body language is another useful possibility.
Or they might use a sexed language, so after exchanging a few words everybody would know where everybody else stands (some Earth languages have different registers or modes to address inferior-to-superior, male, female, young-to-old and vice versa). Lots of possibilities there. I remember once a young English friend visited and "taught himself" some Italian words, without noticing that Romance languages are gendered while English isn't - I am happy to see you has two different forms for happy depending on whether the speaker is male (contento) or female (contenta). Gleaning words from his female cousin, the poor boy started talking as a girl would.
really avoiding gender
But say we don't want to have any outward expression of sex - of gender. Can we still efficiently select for mates? Apparently we can't.
How do we cheat?
Ursula K. LeGuin created a world, Gethen, where humans are hermaphrodites - they have only one sex (at most), but which one depends on how they experience kemmer, a periodic hormonal imbalance that can make them either male or female. This characteristic is shared by the regul, aliens in C. J. Cherryh's Faded Sun trilogy, but the sex choice (which happens once and lasts for the remainder of a regul's life) may be influenced by pheromones.
So, your society is genderless and normally people do not even have (external) sexual organs (this is the Gethen norm). Any two persons may meet and fall in love or feel attraction for one another. When they do, and stay together for a sufficiently long time in a sufficiently intimate context, their bodies start reacting to one another (this is the Regul mechanism), choosing two complementary sexes either at random or based on their physiochemical characteristics - who knows, maybe the one healthier, larger or with more body fat becomes a female, to maximize chances of carrying out a pregnancy. The more sexed the one becomes, the more sexed the other (but with opposite gender).
Should the language need to reflect this, it would need male, female and neuter mode, like the Stsho of Lyene (another C. J. Cherryh's creation, in the Chanur series) do. They might then maybe say something like "When I-neuter saw it, I-male asked her out" to emphatically describe love at first sight.
The maximum efficiency is then attained: whoever your potential mate is, will always be sexually compatible because it's your potential mate.