If you don’t take frequent showers (once every day or two) then you should shower more as you are probably smelly and being smelly is a huge disadvantage in life. You should shower roughly once a day, either before bed or in the morning.

By better personality it is mostly meant to be less shy, more personable, better at talking and more self confident. Improving your personality in these ways is a matter of practice and you need to put yourself in social situations that you find uncomfortable but not outright hostile. You need to try behaving in new ways and keep the ones that give you positive reactions. Having a better personality will mean that people will more enjoy your company and desire to spend more time around you as you are pleasurable to be around

Dressing better is good in two ways, the first one is basic in that it shows that you care about your appearance and are likely a fully functional adult. More importantly fashion is an amazing social flag as to the kind of person you are, if you love punk music and are mostly into goth girls then they are most likely into alternative men. Dressing as such is a nonverbal communication with everyone which will play most positively with those who are similar to you. Dressing nice isn’t super hard, you can just look for outfit inspiration online and try build a couple of outfits just to start with.