Just a couple of tips to help you get your suggestion across and possibly accepted!
1) Be Clear and Concise: Sometimes, less is more. If you need to type a few paragraphs that's fine, but try to avoid repeating yourself or dragging on. Get your point across.
2) Include Plans: Try to at the very least spitball or pitch some ideas on how you want your suggested or added feature to work. If it's an item what sprite would it have or what would its function be? If it's a feature, explain how you imagine it working.
3) Sell It: Tell the dev team why your suggestion would make the game better. Why do you want it? Make the devs want to bring your idea to life as much as you want it to live.
Got a few tips of your own? I'll leave the thread open for contribution for now.