Amazon FBA online arbitrage sourcing question

What do you find to be the best strategy for sourcing OA items? I have used manual and reverse sourcing and Tactical Arbitrage.

I found majority of items with TA but I find it is very hard to find good items that don’t tank for a few months before even coming close to my asking price.

I make sure the keepa looks good and steady price and everything, but I think the issue might be everyone else is seeing the similar results through the search database and items just start ranking.