Advice / pointers on replacing valve seal

Make sure it's big enough in diameter that none of it gets stuck under the valve when you reassemble. ( I get rags stuck between the seat sometimes at work).
There should be a seal installer but i don't believe they're necessary unless the valve tip is rough
If I remember correctly the seals are not difficult to put on if it's a positive seal then just use a socket that is probably around 7/16 or 1/2 inch or whatever works. I do head rebuilding everyday but never changed a seal while the head is still on the engine.