Realize that there is no need for a separate organization to manage "Human Resources." This is an outdated concept and it wrongly, unnaturally displaces responsibility for developing people from managers to bureaucrats. Put basic developmental tools in the hands of managers and demand high standards for your company's culture.
At our company, we combine personality testing (during recruitment) with ongoing 360-degree feedback as basis for development. We complement this with an experienced outside advisor that coaches and consults with our full management team and with groups of employees. We do not rate or "score" or topgrade individuals in any way. We recruit great people to spend their whole careers with us, and we take our time to hire with many stages of screening and project work before offering a fulltime position. Every one of our employees in 9 countries gets a robust development plan and access to advancement, training, and profit-sharing... and we have no HR department.
We still have our share of challenges, but at least everyone feels strongly about our culture and our value of personal responsibility for development.