I want to watch Deadpool, but I have heard the character has appeared in X-Men series too. My question is, if I watch X-Men before Deadpool, will it enhance my interest in the Deadpool character?
To understand the film, none.
Those jokes and all the other references (almost) are listed in this Movies & TV answer. (It’s full of spoilers.)
Colossus's character did appear in X2, X-Men: The Last Stand and X-Men: Days of Future Past, but none of his past roles have any importance for this film and he is even played by different
Note: There are many non X-men film jokes/references too like Green Lantern, Taken (film series) etc etc which you can check from above Movies and TV answer.
Deadpool only appears in the movie X-Men Origins: Wolverine, as Deadpool. and this representation of Deadpool is different to the rebooted origin story of Deadpool, as told in the newly released movie.
If you want to know more, albeit alternate, backstory on Deadpool/Wade Wilson, then I'd recommend you watch it.
But you can comfortably watch the new movie with no knowledge of Deadpool as it contains a well defined, new origin story for the character.
As detailed here, only X-Men Origins: Wolverine featured a character called Wade Wilson/Deadpool.
Obviously we have no idea what will enhance your interest in Deadpool, but the new Deadpool movie has no continuity links with that movie.
If you’re entirely unaware of the X-Men series of movies, a couple of the references and jokes in the new movie won’t make much sense to you. But as long as you’ve seen one of X-Men 1–3, and either First Class or Days of Future Past, I think you’re good on that score too.
As Ankit said, you need to see nothing to enjoy it, and X-Men: Origins will allow you to get some of the jokes about that.
But there are like 2-3 jokes about Ryan Reynolds being also Green Lantern that you would really enjoy if you see Green Lantern first.