Here are a few things to consider:
Try to keep propeller-style power heads covered (maybe with foam or pantyhose) so that the anemone doesn't get shredded if it lets go.
I feed my anemone a chunk of krill once a week and it seems to be doing very well. Feeding too much or too large of pieces will cause the anemone to struggle in digesting.
Try to keep water parameters as stable as possible. For this, it's better to have a larger tank, but I've managed to keep mine in a 12 gallon for 3 months with a lot of success.
If you have a pair of clowns that will host it, the chances of survival will increase. Clowns feed the nem (by pooping), clean it, aerate it, and in some cases mine even drags the chunk of krill into it when I drop it into the tank. Hope this helps!
EDIT: Another thing to add... As far as appearance goes, stringy tentacles mean the anemone might be hungry. If the tips have bulbs, the anemone is typically content. If it is closed up, it may be pooping.