Chris Silcox just released a great tutorial on everything you need to know to build your way up to a wide arm handstand.
Chris recommends starting with a partial handstand press and gradually increasing the length between the arms. Once you feel strong and confident enough, put your knees on an elevated platform, hands on the ground and practice the same thing. Once again, when you feel ready for the next step, add a mat or choose a higher platform and do the same drill. Once you add another mat, your hips will be over your shoulders which will help with strength and balance.
Don’t forget to to use your fingers and hands to balance while in a wide arm handstand. For more tips on advanced hand balancing, be sure to check out The True Art and Science of Hand Balancing.