As you said, you're new, so a few tips to get you started, seeing as how nobody else seems to do this.

1. Go look at other suggestions that have passed, or ones that come from common suggestors. You need links to trades depending on what you're trying to do with the item.

2. Once you've gathered that proof, organize it and post it as a suggestion. Be sure to check dates of the trades to make sure they're still valid.

3. There's no shame in a suggestion not passing as long as it was considered. Learn from your past mistakes and you can make suggestions like anyone else here if you put the effort in.