If you're making changes to your house, you shouldn't start until you have planned where everything is going to end up. A variety of computer-based design programs are available; and while you could draw your plans with paper and pen, computer floor plans tend to look cleaner and be more accurate.
Take measurements of the area you plan to remodel. You need the length and width of any rooms, as well as locations of doors, windows or other obstacles in the room. Consider things like fireplaces and counter tops.
Open the software of choice and start a new project. If using Excel or Google, open a blank worksheet and set the columns and rows to be equal sized-squares, noting that they will be square feet or meters. If you are choosing to do the plan on paper, get out a sheet of gridded paper.
Draw your rough plan of the room on your sheet of paper or on the computer. Start by measuring a square or rectangle to the dimensions of the room. If you are using a spreadsheet, use the cell fill tool to paint the room a single colour. Mark any of the other objects in the room like doors and windows. Use the software tools such as the border tools to make these, and label them by typing into nearby cells. Note the direction and distance of door openings.
Measure furniture or cabinets if you are adding them to the floor plan. Measure the fixtures like refrigerators and sinks.
Indicate all of the furniture using the software tools. In Excel, use the Draw tools to make squares based on your measurements. If you right-click on an object, you can also add text--it's a good idea to label the objects so that you can identify them later. If you are using pen and paper, cut out pieces of furniture from construction paper.
Design the room. On the computer, drag and drop the furniture to its final position. Place first furniture that cannot be moved; for example, sinks need to be where their fixtures are. Next, place the furniture that needs to be attached to the walls. Work your way into the middle of the room, leaving any optional furniture for last.
For irregularly shaped walls, such as ones at an angle, you can still use Excel: Draw the square as usual, measure the surrounding walls and draw a line from those measurements. While you can make circular shapes on a spreadsheet, you leave round shapes with square edges. It will be easier to measure and ensure that people can move around the object when placed in the room. Leave room for doors to open. If you will be hanging things like cabinets, you can make a ceiling plan as well: copy the room design and label it "Ceiling Level" and the original as "Floor Level." Note the location of lights on the ceiling plan.