1. For Nする verbs, leave off the し: N次第. E.g. 用意次第、 勉強次第、到着次第 DIJG pp386-7; cf 総まとめN2文法 pp 64-65
2. いらっしゃる becomes いらっしゃり次第；　おっしゃる becomes　おっしゃり次第；　なさる becomes なさり次第
3. Don't use past tense in main clause.

It is also possible to leave the し attached to Nする verbs. （新完全マスターN２、3課）

After talking with my Japanese co-workers about する verbs with this pattern, they told me that you are supposed to leave the し. However in terms of practical use a Japanese school teacher told me that Native Japanese speakers will often change する to できる when using this pattern.

Ngay sau khi/Chừng nào
『次第』diễn tả ý: sau khi thực hiện một hành động hoặc sau khi xảy ra một sự việc, người nói lập tức thực hiện hành động tiếp theo. Vế sau sẽ thể hiện ý chí, nguyện vọng của người nói. Cấu trúc này ít dùng trong hội thoại thường ngày mà hay xuất hiện trong môi trường công sở hoặc các thông báo.

機能：時（すぐ）

形：V（ーます）次第＿＿＿。

意味：＿＿＿たら、すぐ＿＿＿。

※V＝近い将来のことで、いつそうなるかはっきり分からないこと。

例文：飛行機は天気がよくなり次第、出発します。

乗り方によって、自転車はとても危ない乗り物になる
"Depending on how you ride it, a bicycle can become a very dangerous

乗り方次第で、自転車はとても危ない乗り物になる
次第で here can also be read as "it's all up to" rather than just "depending on":
"It's all up to how you ride — a bicycle can be a very dangerous vehicle."

次第で carries a stronger sense of "it all hinges on X" — there's an emphasis on X being the decisive variable. It often implies a motivating or cautionary tone: "it's up to you."
によって is more neutral and simply states that X is a contributing or varying factor. It's also used in many other contexts (passive agent, means, cause) so it doesn't carry that same "it's all on you" weigh

その直後。~したらすぐに…