Do you struggle to get her to sleep or to sleep longer, or both :)
When my baby was about 9 months old, I really struggled to get her to nap in the first place. She was a big nap resister. Eventually, I found the best way to get her to fall asleep was to strap her in the the baby carrier (I have a Catbird pikkolo and had her front facing forward) and go for a slow walk outside. It usually took less than 10 minutes before she fell asleep - I guess the gentle motion and fresh air helped. Then once it started getting cold, I used to clip a blanket on to the carrier and over her head so she'd be kept warm, and I found that she fell asleep much quicker (maybe because she couldn't see anything, or she just knew the routine by then),
The biggest challenge is being able to get baby out of the carrier and in to the crib/ on to the bed once you get back home. It takes practice and of course depends on the baby carrier you have. I used to only do the transfer after she'd been sleeping at least 20 minutes as I found it less likely that she'd wake.
A surefire method that worked for me to get her to sleep longer, was for me to nap with her. She'd nap for three hours sometimes, and of course it was good for me to catch up on some sleep, too! (Note: we co-sleep, so this may not be suitable if you're not comfortable sleeping with your baby) After she fell asleep in the baby carrier, I'd transfer her to the bed and then sleep next to her. If it was dreadfully cold outside or she wanted to nurse, I'd sometimes just nurse lying down next to her , then unlatch her once she fell asleep.
Lastly, perhaps you can read and try some of the techniques in Elizabeth Pantley's No Cry Nap Solution, or No Cry Sleep Solution? (I borrowed both of these from the Vaughan Public Library).
There's also some extracts from all of her "No Cry" books that you can download for free from
http://www.pantley.com/elizabeth/links/PantleyNoCryBooklet.pdf