In photo shop you choose the image size and it gives you options as to what size to make it and you useally go 200kbs at a time but its not allways nessisary to do that . Try shrinking it to the file size you want then save it as a jpg (AFTER THE CONVERSION) you only really should change it to jpg at the final stage. You have a option at that time ( 1- 12 ) jpg conversion ratio . useally a 6 or 7 will give you under 200 kbs at this point with out to much jpg loss. Your first render was fine but the lighting looked like she should be at the beach and not the woods the second is better or from what i can see for the woods .