Earnest

Welcome to the forum.

Tell us more about what you are doing.

Lots of good tips here from experts.

Tell us what kind of problems you are having.. What does your weld look like and what does your instructor tell you?

What position are you welding in?

What diameter of electrode are you using for fill and cap?

What amperage are you using for fill and cap?

Let us know those things and the answers will come.

Clean your root pass well. Remove your slag and undercut. Power wire brush the root face. If you are running 7018 for the hot pass then use 3/32 and run it moderate heat about 90 amps. Oscilate enough to tie in the side walls without burning thru or undercutting the walls. Clean each pass/layer well. Try to keep each pass/layer pretty flat. Not convex(humped up) That makes the next pass more difficult and risky. Shouldn't have to grind much or any after the root pass. But if you have porosity, trapped slag, knots, bad starts etc use the grinder. You can split pass or weave the cap on vertical test but OH, F, H use stringers or slight weaves. You should also use 1/8th when able to. If you are welding steady your plate may get very hot so before you cap it you may want to let it cool a bit. Your caps should be about 1/16th to 1/8th above flush.
A little more info from you will help us give better advice.
Good luck with it.