What size cake? What oven temp? What recipe? All things are taken into consideration...is it just the top not level or one side? I don't use the strips I only use the nails.
I don't use strips or nails. Cakes will dome a bit to a lot depending on the factors asked about in the PP. You can always level with an Agbay or a knife.
As has been said there are many 'tricks' one can try. Are you putting enough batter in the pan? What temp are you using to bake? Scratch or box mix batter? Sooooooo many different things can effect the outcome of baking a cake.