We have a few common interests such as investment, and sports. We have a few common interests such as investment and sports.

As you only have two examples of common interests it makes more sense to use and rather than a comma.

To be honestly his investment knowledge is terrible. To be honest his investment knowledge is terrible.

DiI wouldn’t say I am good. I wouldn’t say I am good.

I wasn’t sure what you wanted to say here. Another alternative could be ‘I wouldn’t say I am knowledgeable about investing’.

But he didoesn’t even know many basic rules. But he doesn’t even know many basic rules.

Unless he now knows the rules, ‘doesn’t’ sounds better than ‘didn’t’. Didn’t makes it seem like he knows the rules now (perhaps because you taught them to him) but I think you mean that he still doesn’t know the rules.

I have laughed at him many times. I have laughed at him many times.

Or you could say ‘I laugh at him a lot’.

AboutWhen it comes to sport we both like snooker. When it comes to sport we both like snooker.

Recently he insists me toed I play a snooker game with him. Recently he insisted I play a snooker game with him.

You need to use the past tense here

Because of his poor knowledge on investment, I did look down at him and thinking he is a worstinvestment knowledge, I underestimated him and thought he would be a bad snooker player. Because of his poor investment knowledge, I underestimated him and thought he would be a bad snooker player.

Surprisingly, his snooker skill iss are way better than mine. Surprisingly, his snooker skills are way better than mine.

Snooker skill sounds strange.

Have you ever gothad a co-worker like that? Have you ever had a co-worker like that?