Most Helpful Guy
Let's try to draw a line here to differenciaty between ugly and unattractive. A person who is physically ulgy (to today's cannon) could even become attractive if his/her personality compensates enough for it. However, there's a point of no return on "uglyness" in which your personality might not even be a compensation. SORRY really ugly dudes and ladies with great personalities, it's a fact!
If you want a more empirical approach, ugly people by definition should be the ones that do not trigger on you sexual attraction with the plus of being able to provoke some disgust to you when thinking about the sole possibility of engaging sexually with them. Someone is not ugly if the possibility of sex with that person does not repulse, even if it does not fancy you. That would be a normal person.
Ulgy people have some physical traits easy to identify: their symmetry is totally imbalanced (a slight symmetry can be sexy), they have multiple irregularities on their skin or have body attributes that are too big, or too small, or that don't go together probably for being too different (i. e. a lady with small breasts and a big butt is less attractive to the majority than a lady with big breasts and a big butt).
Another definition which complements the beauty of a person, is related to evolutionary reasons, not only to society standards. As such, a man with a strong body, particularly well shaped abs and a well defined butt, is more attractive because he will apparently perform better in the act of sex than a chubby one. A woman with bigger breasts will be more suitable to feed offsprings, and the one with bigger hips will be better to give birth.
If you think that the social standards are playing tricks on us by what I mentioned in my last example, beware that youth in girls is also related to fertility. It is no surprise that men in general feel more attracted to younger women than older ones, even if the older one is smoky hot and the young one is average. On the other hand, many women feel more attracted to older men, even when they don't exhibit perfect bodies, as they impersonate better the figure of the protector and provider. Obviously women like young men because they usually have fitter bodies, but it is easier for them to get "hooked" by older ones. Beware that all that I'm saying here is related to evolutionary psychiatry, and that yet, it has exceptions which are affected by many other variables.
Most Helpful Girl
Personality wise - people who refuse to be accountable for their actions and take responsibility for the fall out. Whiney people who think they're entitled to anything at all when they've put no effort, thought or sacrifice into it. People who put others down to push themselves up, and those who speak down to others (like waitstaff or housekeepers)
Physically, poor hygiene and general unkemptness is unattractive to me - but so is the complete opposite when people overcompensate with a pancake of make up, guys with a huge bouffant and a can of hairspray etc
Enhance natural beauty, don't try and look like a completely different person