It is important to include a degree of humour in your writing and it is Sunday so I thought that I'd share a little with you.
Humour can be difficult but as I often have said in this forum it is a humanising element. It has many forms ranging from sarcasm to slapstick, but emotion is what you're trying to trigger in your readership. In some degree it helps to sell your books alongside genre and a plethora of other factors.
The relationships between your created characters opens up the opportunity for dialogue in which humour can be introduced and will engage the readership. Like all aspects of writing it is important to read a variety of material to experience all aspects of writing. One of the most amusing writers I have ever read is Tom Sharpe who wrote the 'Wilt' books.
Tom Sharpe (1928 - 2013)
The humour is not bawdy, rather quite clever, but does have you laughing out loud and I can recommend this writer's books.
There is a sequel but other works include 'Porterhouse Blue' and 'Blott on the Landscape' all well worth a read.
Obviously, don't get bogged down with the humour if you are writing a different genre.