with comparative success

Is it correct in English to say you do something with comparative success? If not, how do you express that you are relatively successful in something, if you wanna say it that way: I do sg with.... ?

Thanks.

You should say "relative success" instead.

"relative success" would be more common, but "comparative success" is also correct. From Webster's Online Dictionary:

Comparative, adjective
2. Having significance only in relation to something else; "a comparative newcomer".