I will be glad to share more with you if you like. Some of the problems I have seen when students of English first attempt complex sentences, is the excessive uses of commas, in which statement after statement is written, when the paragraph could be more effective if brief individual sentences were used.
Complex sentences are usually the art of a more advanced writer. Badly composed, they can present a nightmare of confusing verbiage. Deftly done, the complex sentence can bring clarity to the expressions of ideas that are not so simple.
--Warm Regards, Bruce