I have a great experience in adding friends on my accounts. I recommend you to add 20-30 friends per day for the first time until you get about 30-50 friends. It takes about a week and that is the safiest way. Then you will be able to increase the number of requests and also you can add mutual friends (by the way it works really impressive). I recommend you don't hurry and go slow from the little numbers.
I use my own software for facebook, but i am pretty sure each software has settings for limitation numbers of friends requests per day. I decribed a lot of things in my journey - http://www.blackhatworld.com/blackhat-seo/facebook/737932-russian-vs-facebook-diary-battle-how-win-gain-money-power-followers.html