Either from my laptop or my andoid tablet I thought first Port forwarding and the pair of keys for SSH would be good but no avail I lost myself.. Thinking that it's easier I tried also Openvpn but I did not succeed either. Moreover Openvpn seems much for my personal use ? I am looking for an advice Thank you
OpenSSH is designed to be the most secure way to tunnel into your machine.
When I say tunnel, I mean connect into the console via an encrypted tunnel, where you can also connect using SFTP over port 22, reroute local ports into you machine to make it look as if you were at the machine while surfing somewhere else in the world, redirect X application but in its simplest form, log into the console as root or another user.
It depends what you want to to connect to the raspi? View webpages as if you were inside the LAN? So no port 80 forwarded to the internet? It takes some configuring but look at this tutorial. Basically the client creates a proxy at your local(outside from home) and anything you want to access your remote(the machine at home) goes via the poxy, into the tunnel and get routed on the Pi.
At the least you need to open port 22 to the Pi and it would be recommended to use keys but if you use a good password, that is enough too.
I think setting up VPN may be an overkill. But it also depends on what you want to do. If you let us know what your purpose is, we may be able to help better.
With SSH I am able to do most things I want do remotely on my RPi. Just to expand on ppumkin's answer, here is a quick work flow for you (of course you may already know this but may help others):
If you want to be paranoid you can have 2 factor authentication using Google Authenticator app.
Read more here http://www.raspberrypi.org/forums/viewtopic.php?f=29&t=61993
Maybe not the simplest way - but I found certificates more difficult.
I can also report that I have detected the scanners are now occasionally using user 'pi' when attempting ssh to my webserver. Unfortunately I cannot change the port number there, but I do block the source IP after two failed attempts.