Hello Ivan, I am afraid ,there is not particular technique for that. The word "tôt" as an adverb means ' early' ,but when attached to other words it gives many times a totally different meaning as in 'plutôt" which means 'quite or rather'. You will have to learn them as separate new words adding up to your vocabulary .You will use the same techniques you usually apply for memorizing new words like repetition, building sentences using them and reading again and again etc.. À bientôt ;)

Bonjour A suffix is a word ending. It is a group of letters you can add to the end of a root word to have a new word. - bientôt = soon - aussitôt = right away, immediatly - plutôt = sooner or rather(depending of the context) You need to learn and memorize them. No easy solution here!