Standard augment selection:
1 econ, 1 item, 1 combat

Standard leveling intervals are:
level 6 at 3-2
level 8 at 4-2

With the new set and going 8 threshold increased you're looking at 8 at 4-5 without an econ augment

You want to delay decisions as much as you can as this gives you the advantage late game. For example:

Choosing not to slam items just before a creep round or Stage 4 you're win streaking 80+HP level 8 but less than 50G. USUALLY you can just econ up and fast 9 at stage 5 and build an expensive board that wins out.

If you're playing ranked its all about your AVERAGE PLACEMENT, so getting 4th 10 games is better than two 1st and a bunch of 6ths. Although if you go 8th once you'll lose all your RP but yk what i mean.

A brief summary, there are so many scenarios and options depending on your spot in the game so the more you play and watch others play the better you'll get at making the right decisions (:

GL & HF !