Real russian dating services
Bulgaria is much safer than Russia with much less violent crime on the streets.
Russia on the other hand is very expensive and not very safe.
Just keep in mind that their motivation for this may not be as pure as you think and you may find yourself wifeless once she has got citizenship/money through marrying you.
If you register at a Russian dating service (also known as internet dating /marriage agency) and find out that lots of much younger women are contacting you eagerly for dating - you will know for sure you have landed at a scam dating website.
Bulgarian women are less likely to have professional photos; they are more likely to take a few quick snapshots with their web cam.