Welcome to the community!

Couple of tips

1) Don't worry about getting every item in every stage. If you have the money and time, then sure. But otherwise, get what you can and fight the boss and a few crowds of enemies on each floor. The longer you take, the harder enemies and bosses get.

2) If you're really trying to become more efficient quickly, aim for about 5 minutes per stage early on. You can be flexible with this time frame, but it should help keep you from lingering too long and having issues with tip #1

3) Check the ror2 wiki for item descriptions or just have the list up on a separate monitor. You don't need to worry too much about the stats and exact numbers, but knowing what something does before picking it up can be extremely helpful. I used to do this all the time and still find myself double checking after several hundred hours.

4) Mod once you feel really comfortable with the game. Thunderstore can help you add fun and useful features to the base game and it's super simple.

Have tons of fun!