How can I prevent bugs from coming inside?

I just moved into a new apartment and I keep finding alot of outside bugs coming in. The apartment is very old so there are plenty of cracks and things for them to get in i’m sure. I am finding things like house centipedes and spiders, nothing else really. I bought some home defense stuff at lowe’s and sprayed EVERYTHING I could that seemed like a entry way for bugs. This stopped things for about a week or so but slowly I am noticing them creeping in again.

I am not sure if the weather change getting cold has a part to do with it but what would be some effective ways to keep them out.

The spray I used seemed to help alot, it atleast reduced the problem significantly but I want it 100%!

I was thinking about getting some weather stripping for the old windows but I am not sure what else I can do.

Any other effective ways to keep these pests out, it really makes me uncomfortable and not want to live here…