Give it a try! Once you do it, you will have mastered the skill, its not really hard - the difficult part is figuring out the steps which I have done for you. You can tweak the formula above if needed, too. Sometimes I will add in toner coats and the like. You can't screw it up, worst you can do is make a mess of things and then take it to a pro. I have literally done the above out in customer's driveway when we've driven several hours to get to their home and discover a nick in the top (I keep a kit in the truck with all the above in it).

One mistake you may have had is using a paint brush and poly. When you first try this sort of thing there is a tendency to COAT IT (Lay it on thick) and that's a mistake. You put your finish products on 'dry' in light layers and build them up, and never use a brush. Most polys I will wipe on with a rag, and at most I will use a foam brush, but never one with bristles as you can never get that poly leveled that way. Maybe One day (if I ever get caught up) I'll make a short video showing how to do this.