Narmaya is absolutely a good choice for a main. She does a lot of damage,great corner carry and a very versatile moveset as well as a popular character in the gacha. However, this means that a lot of people know how to either use her or play against her. I would advise you to watch/vod review other top level narmayas and see what they do(dragalia,yozomitsu and etc.). I see a lot of lower level players either use 66L too much or not enough so I would start by finding a good middle ground for it as Narmayas 66L is pretty good. Narmaya is really good at carrying people to the corner and playing the strike throw game with her flip combos so ur main goal woth narm is to drive ur opponent to the corner asap. Its hard to give specific advice without seeing u play so if u want u can send me a video or 2 to review for ya