If you want to market a merchandise successfully, you must know the merchandise. The same is true in marketing personal services in Java/J2EE.
Ability look at the big picture
Ability to think not only from the technical perspective but also from the business perspective.
A good understanding of the key areas of software design/development.
Communication, interpersonal, presentation, leadership, team work, being pro-active etc.
Everyone wants more money, but it is something entirely different to be worth more!. Your value is established entirely by your ability to render useful service or ability to induce others to render such service. Before you even start to negotiate your salary be sure that you are worth more than you now receive.