QUOTE
Marvelle dried her tears. She sat on her bed, clinging to her china doll crying.
Could be "Marvelle had dried* (or rather, "was about to dry") her tears. She sat** on her bed, clung to her china doll and cried" or "Marvelle will (be?) dry(ing?) her tears in 20 minutes. Just prior, she'll sit on her bed, and cling to her china doll [in awe of what she'd just done***] (obviously she's crying, you've already revealed that)".
When you word it like you are, it tells the reader that something is happening right now, obviously, you can't do the whole story in present tense, or it doesn't make sense (to be fair, even if you do it all in past tense it sounds dumb, but I can see in certain context it could work for future tense). You have to choose the future or the past as your tense... but I guess, since this is an exersise, it's not supposed to be entertaining, but develop writing skills.
When you do one declarative sentence after another it sounds really bland no matter how you word it. Also, try to use more powerful words, obviously if she's clung to a doll she's unhappy, so there's no mystery if they're 'tears of happiness', so you could use words like weep instead, maybe even mourn, as if to forshadow something bad had happened.
I'm not an expert, but I know that if you state one thing at a time, it get repetetive and annoying. For example "The car in the driveway was blue. The car pulled out of the driveway and sped down the street. It left a trail of smoke." That's just ****ing stupid. If you want to do something like that, you have to have the reaction of a character (1st or 3rd person omnipotent, it doesn't matter), and that characters reaction should be unique, or foretelling of an event soon to come.
*verb
**past tense, don't mix past tense with present
***foretelling, can make reader wonder what happened, thus, continue reading... I stopped about here when reading yours and decided to try reading a few sentences backwards to see if they made sense, and they did.