Poemap works very well for trading white tier maps, OK for yellow and poor for red. So make sure to use it a lot at the start to fill out your atlas and get the large chunk of whites done.
For trading I like Trade Companion:
https://github.com/lemasato/POE-Trades-Companion
You've seen these before in trade where someone has an automated thank you msg and they kick you from the party. You can read up on the features but the quick list is:
- 1 Button invite
- 1 Button It's Sold
- 1 Button Please Wait
- 1 Button Thank you and kick them
- 1 Button leave party and travel back to your HO
- Highlights item that they want in your sell tab
- Tabbed notifications so you don't get confused when multiple people are trying to buy from you
Sometimes I also install Trade Macro:
https://poe-trademacro.github.io/
It has a basic and an advanced search function for pricing. The basic function works great on items that are set like div cards, scarabs, etc. If you're searching rares or uniques with large roll ranges then you need to use the advanced box and tick off ranges and stats. If you pickup and try to sell a lot of items then this is a good tool to have. If you tend to only sell large ticket items or sell infrequently then it's not that helpful.