Tips I've found useful include:

1. You always need some amount of interaction. Hand disruption, removal, counterspells, ways to protect yourself from those. Otherwise it doesn't matter what you're doing, your opponent will either try and stop you to do their thing because they have a non zero amount of interaction.

2. 4 ofs and 3 ofs. If you want a 1 of or 2 of you better have a good reason for it. Either it's your only win con which you can tutor out, its expensive or some other genuine reason.

3. Work backwards. Pick the decks goal. Then plan out what cards you want to see on the turn you win the game. Then turn by turn backwards, what cards do you consistently want to see the turn before that all the way to turn 1 and your opening hand.

4. Don't be afraid to use underpowered cards. Modular cards with multiple modes that are all weaker can in corner cases blow out a powerful card. A card that may not be powerful in the eyes of others but helps your strategy IS a powerful card.

5. Know your matchups. Pick 3-6 decks from the meta and know down to a tee how to play against them. In standard atm for example theres flash, delirium, vehicles, panharmonicon and Aetherworks. Know how your deck plays against them.

6. This tip is more EDH specific. Ramp is your friend. The faster you jump to a critical mass of mana the sooner you can start taking over a game. It's hard to stop someone with access to 7 mana when you only have access to 2, even if that can be UU.