HI I m going to start a social network site, (with socialengine) which kind of hosting plan i should use,,, dedicated server?
For a site that is brand new (with little or no immediate traffic), it may be best to start off with a simple shared hosting plan that almost ever provider offers for nearly the same price; take your pick. There's no reason to pay for a dedicated server until you are consuming more resources than a shared plan can offer, at which point you may consider upgrading to a VPS and so on. The savings would best be allocated to an advertising budget .
Starting with a Semi-Dedicated account or VPS server would be better due to the uptime being much better, which is very important when starting up new Social Networking kind of sites. You could get away with using a standard Shared hosting plan with a GOOD provider though.