Use a silver coin as the planchette, or wear an article made of silver. The silver is supposed to protect you from evil spirits.
To improve "reception", use a solid wood board work in male-female pairs.
Drawing a circle around you and the board, or making a circle of candles on which you concentrate on creating a safe, protected place might drive away or keep at distance the evil spirits.
Always say goodbye to the entity you are talking with when you want to end a session. If you don’t say goodbye, and the spirit doesn’t reply in kind, he may be trying to stick around and harm you in some way. Do not explicitly invite the spirit to enter someplace, since this will make it hard to get rid of him later.
Sometime, a “writer” that will not touch the planchette is necessary to transcribe the session as the pointer starts moving too fast for you to read and process the words it’s spelling out. Another way to transcribe is to have someone call out the letters to a tape recorder. Don’t take for granted or literally anything the board says. Ouija boards are famous for lying or otherwise giving false information.
Spirit are trying all the time to communicate with us and will take every opportunity to do so through whatever means is available, and this includes Ouija boards, remember not all spirits have good intentions, there are mischievous or negative spirits around.