Practice SH angled fairs and bairs. I find the diagonal->up angle to work best against full hop approaches and high platform drops. The diagonal->down angle works best for retreating short hops and short characters like pichu. The better you can get at spacing out SH to land tipper the more knockback and shield damage you're gonna get. Also SH fair or bair into f-tilt I feel is pretty solid for really aggressive opponents.
Mixup your Cross and Axe and don't just sit in one place tossing them out (unless you have a platform above you, making it harder to approach). Especially on tri-plats, mixup tossing out Cross at SH and FH height and Axe at short or long distance depending on how your opponent likes to approach.
And remember, bair tipper does more knockback!