Most managing partners of law firms with whom I have spoken have said that the number-one attribute an attorney must have is an outstanding legal skill set. This should be developed over time at your law firm. You have to be able to write well, know and understand the law in your practice area, and be able to explain the law to attorneys and non-attorneys.
If you feel that you are not getting the proper skill set, you should speak with the partners or professional development attorney to assist you. If that does not solve the problem, you are likely at the wrong firm.
2. A Good Mentor
It is important that you have a good mentor at your firm who is patient and willing to teach you. It is difficult to come up through a firm on your own. You need guidance and good feedback on your legal research and writing skills. You need a partner to give you good work. You will also need partners who will speak up for you at the partnership/review meetings.
3. Billable Hours
It is imperative that you at least hit your minimum billable-hour requirement. If not, it will be very difficult for you to make partner at your firm. I understand that most times you do not have control over the business coming in the door, but you should try to align yourself with partners who have busy practices.
All things being equal, those associates billing 100 hours or more above the minimum billable-hour requirement will likely make partner over associates just hitting the minimum. It's a very good way for partners to distinguish one associate from another.
4. Thriving Practice Group
On your quest for partnership, it is very helpful to work in a practice group that generates significant revenue for the firm. When other associates are put up for partner, you are likely to have more billable hours, and the partners in your group will have more leverage because they are very profitable for the firm.
Law firms are businesses. If one partner is generating $2 million a year, another partner is generating $600,000 a year, and they both have associates who are up for partner, most of the time the associate with the partner generating the most revenue is given preference.
5. Business Development
Although there are some law firms that have very high billing rates and institutional client bases and therefore do not expect their associates to develop their own Fortune 100 clients, all firms expect you to get involved in the community. Getting involved on boards or committees will lead to contacts and may eventually lead to business down the road. Those associates who are able to generate/originate their own clients will have a much easier time making partner.
Another way to develop business is through meeting partners and associates within your own firm. This way you can take advantage of possible cross-selling opportunities within your firm.
Honestly, those who develop their own business are able to control their own careers within the law firm environment. You may be elected to non-equity partner without business, but don't you really want to eventually make equity partner?