These are the main tools I think you want to focus on:
- short hop fast fall L-cancelled tipper forward and neutral airs
- wavedash downtilts
- tipper forward tilts
- tipper up tilts
- dash dance jump cancelled grabs (or wavedashing in shield to a jump cancelled grab if you are technical enough for that)
the SHFFL'd f.Airs, n.Airs, and the up tilts are fast close range tools that easily combo. the up tilt is the strongest combo starter at low percent while the fair and neutral are better for mid-percent knockback to get them on the ledge and set up a ledgeguard situation. the forward tilt is the strongest tool to very quickly and fairly safely knock them away from you and get some space (SHFFL'd down air out of shield is also a good option, only do this if you are very consistent with L-cancelling it however). the dash dance grab game will make them respect your space more. also, if you're avoiding their lasers, never approach with jumps while doing so, really unsafe. you either have to take the lasers or shield on the ground and wavedash/dashdance in. unless you're really good at using down air to spike, use forward smash, forward tilt, and shieldbreaker as your primary kill moves.
also note that if you can't SHFFL, or you can't wavedash, most of the moves are still good. if you can't L-cancel properly, all of your aerials except down air will auto-cancel fast enough to make them safe with a non-fast-falled short hop. just don't fast fall, or some of them can be punished easily. short hopping should really be a priority if you can't do that though. i would definitely learn to asap.