You can represent yourself in practically any legal matter. Since, you're not obliged to hire a lawyer for legal advice or to complete a business or personal transaction. Thus, a person who is charged with a criminal offence, however, will seldom appear in court without a lawyer.
Therefore, it's wise to know the consequences before you take action. Since, a lawyer can offer an objective and impartial point of view and tell you what to expect. A lawyer's advice can also guide and confirm your decision or lead you to consider new or different options.
Since, specialized training is required to understand the legal complexity of a will and power of attorney, for example. It's very unlikely that you will know how much you or your estate may be charged if your will is contested or problems arise. Thus, when important things are at stake, informed decisions are the best decisions that you can make. :o