How should I approach using undersized weights?

Hey everyone, I have been trying to get into shape recently and had a few questions. The last couple of weeks I have been doing some cardio and light exercise with dumbbells. My concern is that the only dumbbells I have are light for my size/weight - 10 lb dumbbells vs me at 6 ft 210 lb. I figure anything is better than nothing so I have been using the weights to do a few simple exercises. I have been shooting for 3 sets of 20-26 reps depending on the exercise. I ordered a new set of dumbbells that should arrive sometime next week but in the meantime is there anything I should be wary of while using the undersized ones?