Initially I try to keep it something related to their profile. Hopefully I am lucky enough to have something in photos to relate to. Sometimes a non-intrusive compliment. The color of a shirt looking good or ask if they got the shades on a vacation. People tend to have a story they like to tell if they wear a signature item such as a pin, cap, or Tshirt with a logo. Tat's can be iffy but usually there is a story behind them.

If they have listed some interests that is a big help. If someone just puts generic interests that are so vague (music, sports, anything outdoors) I might say something that narrows it down a bit and see if I can leave and opening for a response.

Sometimes I will ask something non-threatening about where they say they are from generally. You can Google the town and get some ideas. Especially if they also list an interest. I am not a golfer but if I know someone is I might ask about a local course or charity tournament, or pro-shop? Guys in the military sometimes will just say that and I will ask something about the near by base or thank them for their service. Mention a respected family member and which service. Maybe joke around about friendly competitions between services. That can be true of fire departments and police departments. ( I have made a point of attending "guns and hoses" events for years looking my sharpest because that NEVER fails to find a few flirty bachelors.)

Guys generally love cars so never hurts to ask someone what their first ride was. It is way less gold digger than the what is your current ride and often tells you what their favorite "brand" is. Playing dumb is lame but questions about cars and so forth are nice small talk.

One thing I kind of only touch lightly is work. People rarely have careers they love and other than being considerate not to keep someone up late on a work night I find most guys think you are checking out their financials and find it offensive. Sad because if you have an idea of what they do all day it can help be supportive later on and sometimes you can have interesting conversations but that is generally further in to a friendship. If they are in a field you know nothing about showing interest by actually doing some reading can make conversations a little smoother.

People tend to be pretty mobile I might ask if they have ever lived anywhere else? Or if they ever thought about living/visiting somewhere their interests suggest. Guys that are into music scene, or cars, or sports know where the "mecca" is so sometimes that leads to conversations about vacations which is generally safe non threatening topics.

I am not a smoker since my teens but I used to ask people what they smoke or where they got their lighters. Profile will tell you if someone smokes or drinks you can usually ask for a favorite brand.

I look and see if people have kids or not. I try to keep the conversation general but usually a question if they have boys or girls is ok, if they are at my age if they have grandchildren. If a person is a non-custodial parent it can be a painful subject so I try to be supportive.

I usually try to read peoples posts because you get and idea of their interests. Sometimes the one word games can be revealing.

Last but not least if you want to avoid scammers and flubbing if you are talking to several it doesn't hurt to keep notes. Remembering someone's birthday or a comment is flattering. Relationships take work and that applies on-line relationships too.