Ahh the art of conversation.
To be honest I'm useless at making conversation, but I've made distinct progress in the last few weeks.
What do ur hobbies include? If u don't have many hobbies, u'll have nothing to talk about. This is the reason I've found it so hard the last few years. I've been playing computer games, basically doing nothing else. It's impossible to make decent conversation in this case.
When around someone, don't be scared to ask questions. People without SA love to talk about themselves and love to tell stories. Ask them about something and expect a lengthy answer if u ask something like "what did u do over the weekend?" If they say something like "I went to Bob's party" without further explanation, ask how it went, who else went, if anything exciting happened, any funny moments, who got pissed the most, who didn't get pissed etc. Make them feel like ur interested in them and they'll love it. If they say they did nothing, ask them why etc.
I know it's easier said than done, because I have SA as well. Sometimes u have to push urself into uncomfortable positions to achieve what ur looking for.
Another good way to make conversation is to talk about what u see and whats happening around u. If they're wearing a bracelet or something u haven't seen them wear before, ask them where they got it, how much it was etc. It doesn't matter if its new or not, u can ask anyway.
Unfortunately for people like us, people never seem interested in us. I'm sure if we ask enough questions, crack enough jokes, make ourselves look presentable and have an interesting life with genuine hobbies, people will become interested. Look at urself in the mirror and ask urself "Would I approach this person and have fun around them?" If the answer is no, try to use a different posture or facial expression to look more friendly. If the answer is yes, ur one step ahead already.