Hi,
After you embed your flow in a Visualforce page, set the initial values of variables, record variables, collection variables, and record collection variables 
through the <apex:param> component.

-This example sets myVariable to the value 01010101 when the interview starts.
<apex:page>
 

<flow:interview name="flowname">
        <apex:param name="myVariable" value="01010101"/>
    </flow:interview>
</apex:page>

-You can use standard Visualforce controllers to set variables by passing in data from a record. This example sets the initial value of myVariable to the Visualforce 
expression {!account} when the interview starts.
<apex:page standardController="Account" tabStyle="Account">
    <flow:interview name="flowname">
        <apex:param name="myVariable" value="{!account}"/>
    </flow:interview>
</apex:page>

-Because record collection variables represent an array of values, you must use a standard list controller or a custom Apex controller. This example sets myCollection 
to the value of {!accounts} when the interview starts.
<apex:page standardController="Account" tabStyle="Account" recordSetVar="accounts">
    <flow:interview name="flowname">
        <apex:param name="myCollection" value="{!accounts}"/>
    </flow:interview>
</apex:page>


I hope you find the above solution helpful. If it does, please mark as Best Answer to help others too.
Thanks,
Ajay Dubedi