Official petitions versus platforms
An official petition through the Bundestag Petitionsausschuss can force a formal response or committee consideration. A petition on a commercial platform has no such guarantee, but reaches people faster and is easier to share. Serious campaigns usually run one of each.
Write the ask as one sentence
Petitions fail when the ask is a mood rather than a decision. Name the decision-maker and the single thing you want changed. If it takes a paragraph to explain what you want, it is too broad to sign.
Convert signatures into letters
Signatures are counted; letters are answered. Ask everyone who signs to write to their own MdB in their own words on the same day. A hundred individual letters from a hundred different Wahlkreiss is a bigger event in the Bundestag than a hundred thousand signatures.