In regards to alcohol the Bible says…
Wine is a mocker,
Strong drink is a brawler,
And whoever is led astray by it is not wise. ~ Proverbs 20:1
I really recommend the following book also which goes into more detail…
http://www.amazingfacts.org/FreeStuff/OnlineLibrary/tabid/106/ctl/ViewMedia/mid/447/IID/70/LNG/en/7/The-Christian-and-Alcohol/SC/R/Default.aspx
After reading that short book (takes less than an hour to read) it is clear to me that alcohol should be shunned. The fruits of alcohol consumption as we can agree are not good. Drunk driving, broken families, abuse, crime etc.

In regards to smoking the Bible says…
Do you not know that your body is a temple of the Holy Spirit, who is in you, whom you have received from God? You are not your own; you were bought at a price. Therefore honor God with your body. ~ 1 Corinthians 6:19-20

Everyone now agrees that smoking is harmful to your health. They even print it on the package! To paraphrase the surgeon general’s statement “warning this stuff will kill you”. Also we are commanded by God in Exodus 20:13 “You shall not murder.” That includes yourself right! The real question is, why would a Christian want to continue smoking and drinking?

In regards to poker, I think again we can agree that because a professed Christian is a full time poker player doesn’t really justify it. After all David committed adultery, we have only one pure example and that is Jesus, amen? I wrote an article in regards to poker and the Christian and I invite your comments…
http://willfults.com/christian-poker/

Even before reading that article, let us prepare our hearts to search the scriptures and be willing to do what God desires us to do no matter the cost. Let us follow the example of Ezra…
For Ezra had prepared his heart to seek the Law of the LORD, and to do it, and to teach statutes and ordinances in Israel. ~ Ezra 7:10

Hope that helps!