More on direct and indirect object pronouns?

After working my way through lessons 4.8 - 4.10 I feel I've got the gist of direct & indirect object pronouns, as in I understand the basics of them. But these lessons felt like a really quick overview and I'll need more practice to really master them. Can you guys recommend any good practice material for this, if not on this site then anything you've spotted on the web that's free?

I usually google whatever Spanish topics I am interested in.  For instance if you google Spanish direct and indirect object pronouns you will get a list of many sites discussing the topic and also providing free exercises (with answers) to work on.  I have used this technique for many subjects in Spanish.  There are many free sites out there with worksheets to try.  I bookmark these sites if I find their worksheets helpful.

Good Luck!