How do I Approach my Opponent With a FF fair?
Nair, Uair Bair???
Or Dtilt Idk.....
But Besides that How do i Grab Safely Without me Having to worry about being Punished?
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Forgot to mentin this on the Topic Title but how to Position Dairs /Spikes.
You can't really grab safely, your safest grab in general though would probably be a retreated pivot grab. That being said, it still won't work if you don't have the read.
In short, nothing in this game is safe
and works all the time, that's no exception to any of Marth's moves, so you'll just have to bait a specific reaction and punish with a grab.
ie. Bait an airdodge using fair ledgetrapping and doing a fast fall pivotgrab instead.
Bait a shield by using a SHFF Fair/Nair most of the time, and then mix it up with an empty shorthop into FF Grab
or Dancing Blade->Cancel->Grab etc;
Dairs always have to tipper in order to spike, that means you can't get too close, nor can you be too far, but I hear most people have the greatest ease using the later part of his swing to do it.
Basically though, practice makes perfect, there's no real shortcuts to it of "just do it this way and you'll get it every time".
Edit: Although getting a good read/frametrap and landing a spike off of it feels amazing and looks great I wouldn't advise going for it excessively, or going out of your way to land one. Doing so can put you in a poor position, where as a simple fair, edgehog, or pivotgrab might be all you need to keep them on the ledge for more damage and knockback that might lead to the KO anyway.