Can I write my own will? Do I need a lawyer to write a will?

Yes and yes. Anyone who has legal capacity can write her own will, but you should not. Estate law is complex and involved. More often than not, a do-it-yourself will causes more trouble for your family in the future because something was not done correctly or the DIY will confuses things more than settling things. That “more trouble” also means it will likely cost your family more money to settle your affairs. Benjamin Franklin’s saying, “An ounce of prevention is worth a pound of cure” applies here too: investing in a solid plan now is usually much less costly than paying to sort things out later. And the peace of mind is priceless.