The Rabbis of the Talmud (=chazal) have given a few practical advices on Shidukhim, i.e., looking for the right spouse. The decision should be made based on two factors, which must be in agreement: our emotions and our mind. In other words, if we have feelings toward a person but the mind says that is not a good idea, or if the mind says ‘yes’, but there are negative feelings toward that person, the Shidukh must be reconsidered.
In the area of the mind, one is advised to make sure that the other person has middot tobot, good qualities; comes from a decent family, and that the communication channels and that values and character traits are more or less compatible. In the Talmud Yerushalmi the rabbis saw favorably to take a bride “from his tribe and (extended) family (i.e., community) lidabbeq beshibto ubmishpachto. (Qiddushin, 4:4) because the cultural and traditional common grounds are obviously greater. Some bad traits should be seen as red flags like: arrogance, greed and a short temper. Those are character flaws which are difficult to correct and one should avoid.
In the area of emotions, the rabbis did not to say that we must feel an immediate attraction toward the prospective candidate, on the contrary, that might be a sign of looking superficially at a person. “Falling in love”, and especially, “love at first sight”, might be a dangerous trap. Because “falling” in love might imply a temporary shutting-off of our mind, indispensable to make a good decision. What the Rabbis warned us against is having an emotional antagonism toward the other person =’rejection at first sight’. If those negative feelings are there, then, one should not proceed.
Most couples I know, the first times they met, did not feel an automatic attraction nor an automatic rejection for each other, they were emotionally ‘parve’ . Then, they invested some time for the emotions to be nurtured, as they interacted as a couple in the dating process and got to know each other better.