If the site drives people away, no amount of SEO efforts will help. If the site looks terrible, find well designed sites in your industry space or niche. If the site is built on Wordpress, or other Content Management Systems, you can easily buy a new theme from //themeforest.net/ for around $35 (for Wordpress other platforms will also have theme stores). If the site is hardcoded, you may need to hire a designer off https://www.elance.com/.