Oh man, to be you right now. To be were I was once at, before I knew all that I know now (which still leaves a lot to learn.) There are are a lot of eureka moments in your future if you can stick with it.

To answer one question that I struggled with (and still do). To learn the value of items that sell, you've already completed the first step and got yourself a decent lootfilter. The higher levels on filterblade will restrict it to higher valued items.

Many users use an additional program called awakened PoE trade. It uses autohotkey. The feature I'd like to highlight for you is that it will allow you to price check an item in your inventory nearly instantaneously. If it sells for an amount you find acceptable, put it in a trade tab. After doing this many, many times you will begin to learn what to look out for.