models.py:
class UserProfile(models.Model):
    user = models.OneToOneField(User)
    first_name = models.CharField(max_length=100, blank=True)
    last_name = models.CharField(max_length=100, blank=True)
    email = models.EmailField(max_length=100, blank=True)
    company_name = models.CharField(max_length=100, blank=True, null=True)
    website = models.URLField(max_length=100, blank=True, null=True)
    phone_number = models.CharField(max_length=100, blank=True, null=True)
    fax_number = models.CharField(max_length=100, blank=True, null=True)
    country = models.CharField(max_length=100, blank=True, null=True)
    address = models.CharField(max_length=100, blank=True, null=True)

    def __str__(self):
        return self.user.username

forms.py:
class UserForm(forms.ModelForm):
    password = forms.CharField(widget=forms.PasswordInput())

    class Meta:
        model = User
        fields = ('username', 'password')


class UserProfileForm1(forms.ModelForm):
    class Meta:
        model = UserProfile
        fields = ('first_name', 'last_name', 'email')

class UserProfileForm2(forms.ModelForm):
    class Meta:
        model = UserProfile
        fields = ('company_name', 'website', 'phone_number', 'fax_number',
                  'country', 'address')

views.py
def index(request):
    registered = False

    if request.method == 'POST':
        user_form = UserForm(data=request.POST)
        profile_form = UserProfileForm1(data=request.POST)

        if user_form.is_valid() and profile_form.is_valid():
            user = user_form.save()
            user.set_password(user.password)
            user.save()

            profile = profile_form.save(commit=False)
            profile.user = user
            profile.save()
            registered = True
        else:
            print user_form.errors, profile_form.errors
    else:
        user_form = UserForm()
        profile_form = UserProfileForm1()

    context = {'user_form': user_form, 'profile_form': profile_form, 'registered': registered}
    return render(request, '.../register.html', context)

def register_page_two(request):
    if request.method == 'POST':
        partners_form = UserProfileForm2(data=request.POST)

        if partners_form.is_valid():

            profile = partners_form.save(commit=False)
            profile.save()
        else:
            print partners_form.errors
    else:
        partners_form = UserProfileForm2()

    context = {'partners_form': partners_form}

    return render(request, '.../register_second.html', context)