<form method="POST">
<input type="text" name="fieldname1"><br>
<input type="text" name="fieldname2"><br>
<select name="fieldname3">
<option value="1">something1</option>
<option value="2">something2</option>
<option value="3">something3</option>
</select><br>
<input type="submit" name="fieldname4" value="Далее">
</form>

<?php 
// массивчик
$types = array(
'fieldname1' => 'text',
'fieldname2' => 'text',
'fieldname3' => 'select',
'fieldname4' => 'submit'
);
foreach($_POST as $fieldname => &$fieldvalue) {
	if($types[$fieldname] == 'text') {
		$fieldvalue = addslashes($fieldvalue);
	} else if($types[$fieldname] == 'select') {
		// .......
	}
}
?>