Independent authors are often preyed upon by publishers. Writing a book is hard but a relatively linear task — write > edit> proofread, but the modern landscape of publishing and promotion is wide open, with a myriad possible strategies and pitfalls. Unsurprisingly, many authors find the prospect of self-managing their book overwhelming and sign up with ‘vanity’ presses. Many of these presses over-promise and under-deliver. With the amount of money they spend on signing up with a publisher, authors could have achieved a great deal pursuing their own promotional plan. There are many resources online to assist with this planning. Jane Friedman is also very helpful.
Independent publishing is hard, but it can be very rewarding. Many of the possibilities are very low cost, your reach is potentially global, an amazing thing in itself.
WorkingType Design has compiled a useful hints booklet for authors, downloadable here.