A scale plan of your space is a good place to start. Measure carefully as accurate dimensions are key and include features that are likely to affect the design, including windows, chimney breasts and doors.
This will largely be dictated by your budget. Some bathroom companies offer a turn-key solution, with everything from planning and installation to decorating included in the price. While this isn’t the cheapest option, it can repay in terns of the speed and ease of your
If you do plan to change your layout, measure your bathroom carefully. Note the position of doors windows and any pipes. It might help to draw an outline on graph paper, or use an online design tool.