Strategy to be good as good as your senior when you don't have a mentor ?

Read and practice

Kill him and take his soul

@spacem good idea, thank you

@BindView good idea also

Adding on to what @spacem said. Read and practice, and make a list of specific people to follow (blogs/books) who are good in your particular language/workscope/industry.

That way, when you come across conflicting ideas, you can refer to your list of specific people, and their opinion on the matter. (Which is largely what a mentor helps with)

@areimus thanks for your idea. It's good.

@Nanos thanks for your good idea