I think freelancer work is good for small orders and personal texts. Translation services are better, as they have guarantees, support, rush turnaround and they definitely specialize in translation for different languages and industries. Https://besttranslationservices.com has pro translators who specialized in Russian translation. They have a lot of benefits you can check on the website. If you didn't work with this company yet, you'll get a 20% discount on the first order.
fiverr.com - you will find too many low-cost translator there.
upwok.com - for best & professional translator. Very expensive though
Go through job portals or freelancing websites. Go through candidate's portfolio and interview them. Give relevant assignment to know the quality of the work and time required to complete the job.
If you have a very large volume, you should work with the translation agency. They can provide fast translation in a short period of time. I highly recommend Ad Gloriam. I work with this agency many years.