My strategy is to use TopCashback for most things and then only the BA e-store for those retailers that do not appear on TCB. I have a seperate browser on my laptop for when I am doing an online purchase to maximise the chance of the purchase tracking. Even then you are always reliant on things working ok at the other end (I don't ever rely on TCB's special deals awarding the extra money due).
Hilton in particular has been very much hit and miss on the e-store in terms of tracking but when it works there is a nice multiple dip on a short stay (around 9% in avios plus HHonors points plus whatever the Hilton promo offer is plus free gold breakfast plus welcome drink). I think a night in the Doubletree Manchester last year effectively cost me about £25.