One easy way to increase your vocabulary would be to learn all the words that are the same in French and English; words which sound almost the same and mean the same thing.

However, beware of the ‘faux amis’ as they are similar in both languages but have very different meanings:

In English En français 


In English En français
a diary un agenda an agenda  un ordre du jour
to stay, to remain rester to rest 

to put down

reposer (se) 


to take an exam passer un examen  to pass an exam réussir un examen
a day une journée a journey un trajet, un voyage 
at present actuellement  actually en fait, réellement
condom préservatif 


preservatives conservateurs
money argent 


small change 


a ring une bague  a bag un sac
a character 

 in a film or a book

un personnage  nature, personality of somebody caractère