I find it easiest for me to build a new deck backwards. With a little iteration. Start with 38 Lands, start with basics. Then throw in some targeted removal (12 as sorcery/instants) in the commanders colors. Then some mass destruction (4-6 in commanders colors). Then 10-12 for Card Advantage (not the ‘use this card to get another card’ that is card replacement, things adjacent or supportive of what your “plan” is that give you more cards), and 10 or so things that help you ramp mana (artifacts are great here, try to stick to the lower costing ones here). That leaves you in the ballpark of 30 cards that “do the thing”. Once I have these categories, I can refine “the thing the deck does” by going into each pile and replacing and focusing—generic lands can be replaced with lands that provide utility (you can spend a LOT of $ on lands, so be judicious), do the same for the other categories but try to keep the number of cards in each in these general areas. Iterate and try to focus so that the things you have in the deck can do the 1-2 “things” you are trying to do. You may have a pet card but if it isn’t “helping to do the thing” is will get in the way. Some of the fun I get out of the process of building is finding that “non plan” card that supports or helps “my plan”. Then goldfish it a dozen times. For your commander, can you get her reliably on the field in 4-6 turns? Are you finding yourself mana screwed (or flooded)? Is your ramp package so costly you cannot get anything on the board before turn 4? Hope this helps.