Hi Miniginny, I would suggest 5, 8, 10, 12 and maybe 15 to start with. You could also buy a set of adjustable dumbells, it's sometimes less expensive. They adjust from 2 1/2 up to 20 or more pounds, depending on the set you get.
You can also purchase adjustable weighted gloves for the times you need to add a little extra. They usually come with 1/2 pound sandbags that you can add, depending on how much extra you need.
Hope this helps.