Well, what "looks good" is very different from one person to another. Some like very minimalistic modern clean looks, while others like sites that have lots to see on the main page, or colorful fun stuff.
That said, I notice you are posting this in the "Ning To Jamroom" forum, so am assuming you are coming from a Ning site originally... like myself.
The Jamroom team created the Ninja (formerly called "Ningja") skin several years ago to help the first wave of Ning site owners get what they wanted and get what they were familiar with in their ning sites, in transitioning to Jamroom.
That was back when I made the move from Ning to JR, so I opted to use that particular skin and have stuck with it.
JR skins are so code-able and available modules (plugins) are so plentiful, that you can adjust just about anything to whatever you need.
I wanted my several thousand members coming from Ning to feel immediately at home when we made the move, so my JR site looks quite a bit like my Ning site looked like, style wise. Yet it's infinitely better functioning and has many additional options. I know I could fairly easily change it to look more clean and modern- but that's really not what my members want. They want to see everything accessible from the Main page and to quickly scan what's new right there.
Here's my JR site for amateur musicians who play the mountain dulcimer, built on the Ninja skin several years ago and has had only had minor content changes applied since then:https://fotmd.com/
Tell us whether your general taste and goal for your site's 'look' is for example: minimal/tech, heavymetal, mom-blog, news/politics, meditation-yoga-spa, vampirefiction, ...etc. :D
...just another satisfied Jamroom customer.
Migrated from Ning to Jamroom June 2015