consider a master apprentice relationship with someone willing to train you in the details and concepts to the combat mechanics and physics of the game.
Read whole way through this thread, and this is first answer I completely agree with.
Also, go Native and play public, preferably TDM or DM as you will get more live fighting time for you playtime, and play as an archer. Take a 1h as your sidearm. Every time you get closed on by enemy, go to that 1h. If you can be bothered, dont even bring a bow but keep with archer class, or crossbowman. Once you can reliably beat anyone you come across with a crabby 1h weapon as an archer, you should have nice manual blocking skills.
And one point if not seen mentioned here:
Attacking: They key to making manual blocking possible against one, two, three and on occasions 4 and 5 enemies is taking a break from concentrating on it, and counterattacking. Blocking nonstop vs real enemies who are giving you no space IS impossible if you lock yourself in a defensive stance vs more than a single enemy, they will just attack simultanioulsy from 2 directions.
Only through Counterattacking do you buy yourself the time and space to allow drastic repositioning, room for keeping your enemies herded, and maybe the option to press your attack and lower the odds against you. Lock yourself in a defensive stance in the game mentally and irl physically with your hand movements, and its just a question of how long can you survive untill someone smashes your "steel cage" of blocks. This said, sometimes a few seconds of total insane steel cage blocking vs 3 enemies does wow them into backing off for a second, giving you room again for the ultimate defensive move, the overhead smash against the unprepared enemy XD.