I'm sorry if this has been covered. I tried a search and didn't find what I was looking for. If there is already something out there feel free to link it and flame me for being a lowly noob. 
So I'm getting more comfortable and interested in trying out some themes but like where my Ally is now so just in case I want to be able to get back to where it is easily. But I hear you all mentioning things like Nandroid and Titanium and sometimes both. So, I'm wondering which is better or both and if both why or there something even better. Also, an abbreviated how to. Thanks to you all - you've been super great and patient with me!

So I'm getting more comfortable and interested in trying out some themes but like where my Ally is now so just in case I want to be able to get back to where it is easily. But I hear you all mentioning things like Nandroid and Titanium and sometimes both. So, I'm wondering which is better or both and if both why or there something even better. Also, an abbreviated how to. Thanks to you all - you've been super great and patient with me!
Thanks again!