Hi Shruti,
I also use Barron's wordlist. IMHO, it's all depend on how much time you got?

If you intent to memorize all 3500 words, you should memorize the 350 high freq words in one week only

Then you can devote one or two months to memorize all the 3500 words.
Well, that's just my opinion.
Cheers,
Zulfikar Dharmawan