It depends on what you are trying to suggest to them. If you are trying to suggest them on making friends, you have to look at the circumstance. What kind of person is that person, why does that person not have any friends, and does this person actually want friends? You'll have to do some analysis of your own on this one.
If that person wants friends, then help them out by being their first friend. Show them that other people can be compassionate, that other people can care for others. Give them a good reason why they should have friends aside from the fact that you won't be lonely. There are more benefits to friendship than getting rid of loneliness. With friends you have someone to count on and trust. You have someone to get information from. Most importantly, you have someone who can give you a different perspective in life and widen your views of the world, boosting up your tolerance and acceptance levels of other people around you.
If this person is you, then I'd suggest trying to say hi to some random people. Try it with someone from the miscellaneous group/clique because they tend to be the easiest to talk to and are less intimidating since they have a little less peer expectations than other groups. Once you start talking to someone and that person talks back to you, then start asking them questions about themselves instead of talking about yourself. Be polite and choose your words carefully. People like talking about themselves so it'll come a bit naturally for them. Plus asking someone about themselves shows that you are interested in them. And if that person starts talking about something that you aren't too interested in, be sure to pretend that you are engaged in whatever they're saying anyway. I know it may sound like it's tricking them, but it's a good way to not offend someone as well as boosting their confidence, making them feel special or better about themselves. People tend to like those who make them feel good about themselves. And if the person isn't you but someone else, you can give them this piece of advice. If it is you, then you should try it.
From then, things can get complicated because there are so many paths that may diverge from here. I can't cover all of them, but if you have any more questions about this, whether this is for you or for someone else, I'll be willing to help any way I can. Although after a while, most of the things after this point becomes somewhat natural. Hope things go well!
