From an SEO standpoint, How is my site? What should I do to improve?

Unfortunately, your SEO metatags are excessive, not only in their number of keywords but simply do not localize your marketability.

Here's an indepth analysis of your current metatags and recommended improvement beginning with <title>, then <description> and finally, <keywords>

1. Current <title>Nothing But Costumes, Accessories Children Costumes MENS COSTUMES Halloween New Born Buntings Plus Costumes PLUS SIZE COSTUMES Renaissance / Medieval Toddler Costumes Tween & Teen Costumes UNISEX COSTUMES WOMANS COSTUMES Lincenced Costumes halloween costumes,adult costumes,childrens costumes,halloween costume,star wars costume,plus size costume,super hero,batman,spiderman,batgirl,halloween makeup,wigs,hats,masks,pirate,pirate wench,barbie,jedi,knight,harry potter,fantastic four,justice league</title>

Google as well as Yahoo limits the number of <title> entries to no more than 60 characters [including spaces between each key word]; anything in excess of 60 characters are simply not indexed!

Relate the <title> to the categories of costumes found in your local Yellow Pages and localize the title accordingly followed by your business location, i.e., ________, New Jersey. And leave out the domain name unless it is a major brand name.

An improved <title> would be:
<title>Costumes, mens, womens, children, unisex, [rental], [new] | ________, New Jersey</title>

2. Current <description>:

<meta name="description" content="Nothing But Costumes - Valentines Day Renaissance / Medieval Spring Has Sprung Mothers Day Fathers Day ----------------------------- Wedding UNISEX COSTUMES Very Funny Costumes New Born Buntings Children Costumes MENS COSTUMES Accessories PLUS SIZE COSTUMES WOMANS COSTUMES Tween & Teen Costumes Toddler Costumes TV & Movie Characters Incharacter Premium Wands & Wings SEXY COSTUMES Infant Costumes Premie Costumes Mardi Gras Halloween Inflatables Matching Doll Costumes Mascot Costumes Judaica Costumes Haunted House Lenox Gemmy Lawn Inflatables lita Prin NothingButCostumes.com - Halloween Costumes for Adults, Teens and Kids - Accessories Children Costumes MENS COSTUMES Halloween New Born Buntings Plus Costumes PLUS SIZE COSTUMES Renaissance / Medieval Toddler Costumes Tween & Teen Costumes UNISEX COSTUMES WOMANS COSTUMES Lincenced Costumes halloween costumes,adult costumes,childrens costumes,halloween costume,star wars costume,plus size costume,super hero,batman,spiderman,batgirl,halloween makeup,wigs,hats,masks,pirate,pirate wench,barbie,jedi,knight,harry potter,fantastic four,justice league" />

The <description> metatag is normally limited to 25-29 words composing a single sentence which best describes what you are offering; it is not merely a listing of products.

An improved <Description> would be:

<meta name="description" content="We offer new and rentable costumes for every occasion, etc. ___________________________________ " />

3. The current <keywords> metatag is:

<meta name="keywords" content="Valentines Day Renaissance / Medieval Spring Has Sprung Mothers Day Fathers Day ----------------------------- Wedding UNISEX COSTUMES Very Funny Costumes New Born Buntings Children Costumes MENS COSTUMES Accessories PLUS SIZE COSTUMES WOMANS COSTUMES Tween & Teen Costumes Toddler Costumes TV & Movie Characters Incharacter Premium Wands & Wings SEXY COSTUMES Infant Costumes Premie Costumes Mardi Gras Halloween Inflatables Matching Doll Costumes Mascot Costumes Judaica Costumes Haunted House Lenox Gemmy Lawn Inflatables lita Prin NothingButCostumes.com - Halloween Costumes for Adults, Teens and Kids - Accessories Children Costumes MENS COSTUMES Halloween New Born Buntings Plus Costumes PLUS SIZE COSTUMES Renaissance / Medieval Toddler Costumes Tween & Teen Costumes UNISEX COSTUMES WOMANS COSTUMES Lincenced Costumes halloween costumes,adult costumes,childrens costumes,halloween costume,star wars costume,plus size costume,super hero,batman,spiderman,batgirl,halloween makeup,wigs,hats,masks,pirate,pirate wench,barbie,jedi,knight,harry potter,fantastic four,justice league " />

Again, the current <key word> metatag entry is excessive and should be revised and limited to 15-20 plural and compound words without duplicating words, i.e., costumes also contains the singular word "costume," etc. separated by a comma [,] and space. I leave you to reedit your current keyword entries, accordingly.

Once you revise your metatags as suggested above, you will noticeably see increased web traffic. The main reason for poor web searchability, is due to excessive [often spamdexed entries] which in turn confuses the search engines. Furthermore, you have to localize your audience, somewhat so that the locals will find your website by typing in the city and state where you store is located.

Good luck!