Not a bad game
This isn't a bad game, it's got better art than a lot of the flashes that get submitted and there are some interesting options, such as the surfboard. In terms of improving your interpretation of the dressup game genre, I would say try to organise the clothing options in a more sophisticated manner, such as pushing a button to see the t-shirts, a button to see the shoes, etc. Also try to add something that players can't get from other dress up games, like an interesting animation, a hidden easter egg, that sort of thing.
In terms of how good the submission is by Newgrounds standards, a lot of people won't like this simply because it's a dressup game with no extra hentai to make it worth their while, and since the dress up game genre is somewhat overdone anyway. You've already said that you made this to accompany your webcomic, so I wouldn't let the reviews bother you: for what it is, this is a decent flash.