You can create a module that configures the system as you need using XML files. I do not think creating a backup of a database and using it as a template is a good option as it will get out-of-date when modules are updated.

In the module's __openerp__.py, You may add required default modules to 'depends': []. Also, you can set 'auto_install': True to have this module installed for all new databases.

Here is a an example that sets some defaults:

<?xml version="1.0" encoding="utf-8"?>
<openerp><data>
  <!-- Activate Technical Features for Admin -->
  <record id="base.user_root" model="res.users">
    <field name="groups_id" eval="[(4, ref('base.group_no_one'))]"/>
  </record>

  <!-- Some configuration settings -->
  <record id="base.group_user" model="res.groups">
    <field name="implied_ids" eval="[(4, ref('base.group_multi_currency')),
                                     (4, ref('product.group_sale_pricelist')),
                                     (4, ref('product.group_purchase_pricelist')),
                                     (4, ref('product.group_uom')),
                                     (4, ref('stock.group_production_lot')),
                                     (4, ref('stock.group_inventory_valuation')),
                                     (4, ref('sale_stock.group_invoice_deli_orders')),
                                     (4, ref('analytic.group_analytic_accounting')),
                                     (4, ref('sale.group_analytic_accounting')),
                                     (4, ref('purchase.group_analytic_accounting'))]"/>
  </record>

  <!-- Set sales and purchase invoice based on picking by default -->
  <function model="ir.values" name="set_default">
    <value>purchase.order</value>
    <value>invoice_method</value>
    <value>picking</value>
  </function>
  <function model="ir.values" name="set_default">
    <value>sale.order</value>
    <value>order_policy</value>
    <value>picking</value>
  </function>
</data></openerp>