Literally anything can be a good opener. The best openers are whatever freely comes to your mind in the moment without thinking about it too much and to get to that state of mind, you need to try and talk to people more often and make some social mistakes. I don't know what it's like being autistic though, so I can't speak on that but trial and error will get you to where you want to be.

Just speak to lots of people, about anything, even if the topic bores the shit out of you or you have nothing to say. Just try, even for 30 seconds. This is a skill to develop with practice. It's not supposed to be easy at first, but if you commit, it will be eventually.

A good conversation opener is just observing something in the immediate environment you both share. E.g., "Looks like they finally finished maintenance on the science building." If she's interested in continuing the conversation, she'll agree or say something related. Go from there.

Another one is asking a woman her opinion on something inconsequential. Just a week ago I dabbed two fragrances on myself, one on each wrist, and went up to this cutie who works at the local art museum and asked which one she liked better. I had her sniff each wrist in turn, she told me her opinion, she was giving me the "look of attraction" afterwards.

This comment might only apply to half of your conversations, but I think there is a part of a misconception in socialization that I wish I had learned way sooner as someone on the autism spectrum:

It is not always your job to hold a conversation.

FOR YEARS I would blame myself for conversations going nowhere.

While I did struggle to told conversations on my end with people that were talking to me, and couldn't keep replying back and would eject as soon as I felt that pressure of failing the conversation, I was misunderstanding something.

If other people aren't also making a conversation fluid, easy, and natural, they probably don't want to talk or are also anxious and nervous.

There were so many times I blamed myself for bad conversations when I was learning and ironically enough, it was an ex that did not like my autism spectrum that told me that "some girls are assholes, and they need to hold the conversation too and not just expect the guy to say everything."

This advice applies to men too but as ironic as it was for her to say that, I wished I'd known it sooner in my life.

I no longer put pressure on myself for conversations.

1. Because conversations are a two-way street
2. I realized that some times I don't have anything to say because I genuinely don't care about that person and there isn't anything I'd want to know about them or keep one going.

For #2 i also used to blame myself but then started realizing I'm also talking to the wrong people some times. And while I might only want one thing from them if at all, if I don't care enough about anything else about them it is really difficult for me to hold a conversation.

Knowing these two things actually really helped me develop conversation skills with less pressure, because I was then only practicing with people also trying to hold one and people I would actually genuinely wish to keep conversing with.

NEEDING it to work is a mindset that makes things come across as weird and unnatural.

You must adopt the mindset that: It doesn't matter if this works out. I give positive energy. If it is not reciprocated, I wish them well and walk away.

True freedom.

Stop looking for 'good openers'. Stop thinking that social skills are a script, and that you just need to learn these 12 openers, these 7 golden topics, and these 9 cast iron closers.

Its a mindset.

Here's something that might help;

Just be friendly, chatty and nice to everyone without expecting anything in return

Stop looking to get something out of every interaction. The interaction is the goal.

Try it - just be more chatty or friendly to everyone.

Yesterday I saw this old guy on a vintage motorcycle so I asked him what year it was 'born' - and then made some very unfunny joke about it being as old as me - he laughed and smiled like I'd make some fantastic joke. I could see it made his day. And then he waved me as he went off and gave it a little throttle to let me hear it.

If you are nice to people they love it. A little bit goes a long way.

From title:

how do i start a conversation with a stranger, what's a good opening

From body of post:

Main issue is that i always run out of thing to say

Which is it?

I feel for you. It was my feeling for many years, that I was afraid I could think of nothing to say.

You don't have to say much of any value to make conversation. I would practise 2 things (and they do need practise to implement well but they can be practised on any person, not just people you want to impress, so practise is easy to get). These two things are harder for people on the autistic spectrum to master, so they are really important to work on. When you do master them, your autistic brain might even actually make you really good at doing them because you will be applying them consciously not just letting them happen.

Practise reacting to them, listening to them and reading them for what to say next. Practise good positive tone and body language when you speak.

Getting these things right makes the person you talk to much more responsive to you and they will usually want to talk with you and say plenty of stuff that you just have to react to positively.

What does this all mean? Well what does the setting bring? Has this person probably had a busy day? Do they look fresh and alert? What do their clothes suggest? Is it raining? Did anything funny or interesting happen to you today? What do you know or think will interest this person? What has been going on in the world that you can ask their opinion on? When they talk are they positive or negative about something? Are they interested or bored by a topic? Do they want to talk or not? look for the signs of these things and learn to read them, read up on non verbal signals in conversation (not just on non verbal signals women give when they want you to bang them -which is as far as most men ever get into the topic).

Now when you speak, assume you are worth hearing so speak positively not arrogantly or humbly, you are worth hearing, there is no need to affect humility or courage in your speech, just be positive. Signal you are glad to be talking to them. Make sure you let them know this by smiling and by open gestured to them. Don't over smile and be over open(this makes you a bit scary or strange), you have to learn to get this right but you will only learn by practising. Make reciprocal gestures to them and show your interest in what they say.

Watch some cool guy breeze into a room and hold the conversation in the palm of his hand. He made the people who counted feel he was worth talking to and he thought they were interesting. He made them feel good and he expected he would. What did he talk about? Probably nothing of any value at all.

The topics will come if you open people up. You know a lot of interesting stuff -almost all autistic people do. When you are relaxed you will be able to think of tons to say but you will only be relaxed when you know you are making people feel valued and value you and this means picking up on them, e=getting in sync with them..