Great looks - including decent clothes, grooming and facial hair, the way you stand and take space around you and so forth - will give you good initial spike in attraction. There is a big difference if she perceives you as attractive guy vs unattractive guy. If you have good looks the initial spike in attraction can be quite huge.
However, good looks are far away from being enough. The initial attraction spike can go away very fast, then what becomes more important is your personality, resp. behavior - the way you talk to her, the way you express yourself, the way you show her whether you are dominant enough... So this second wave of attraction is much more important than good looks. If a guy doesn't have good looks but has personality, he is much more succesful than good looking guy without personality...
So, most guys are most likely thinking that they should look hot first, and then they should have great personality. That is however somehow incorrect logic. The problem with great looks is, once you look hot (or too hot, too sexy,...) you have to PROVE yourself to the girl with personality.
Say that she sees a hot guy, so she expect hot personality. If he doesn't meet her expectations she will fall into autorejection very fast... I'm talking seconds, you can even see it in her face.... So the spike of attraction goes sharply up - say from 0 to 90% in couple of seconds (when average is 50%). But then if you don't prove yourself as a hot guy that meets those 80-90% of attraction, and the spike goes sharply down, from 90% easily to 20%... Dumping ground occurs, she will not go for a date with you, she may even get disappointed... You will be perceived as great looking guy - who has no personality...
Much better way is to look good, just little bit better than average. This way you will still project good initial attraction, say from 0 to 60%, but at the same time you don't have to prove yourself necessary as a "hot guy". At this time you are just a good looking guy, but she has no clue about your personality, she is curious to find out... So once there is good intitial attraction and she shows interest, you then incorporate your personality, your behavior... Now you can go easily to 70-80% and stay at this level of attraction much longer... You will be perceived as good looking guy with quite interesting personality...
That is why so many newbies have such a hard time. They put on great looks, all the sexy smiles, dominant looks and walks - and then they start talking to the girl with average attitude... She then realizes that most of the appearance is just sort of fake, he simply doesn't meet his appearance with his behavior, there is no congruence... Dumping ground, no return texts, more flaking, more excuses, more headaches from rejections...