What is the best way to ask for a draw in chess?
Orally, depending on the situation, you could use the following phrases

咱们要不和了吧？
我不想下了，就算平局吧。

和 means 讲和，which just implies 平局。The second expression would be more casual and is suggested to be used with close friends.
Above is how you would ask for a draw if the situation is really tied and both of you are tired, if you are feeling that you are losing, of course you would say

咱不下了，我认输了！