It ll depends on what your Swordsmanship is at. I don't know how high your skill is now so I'll give a list on what to fight and when.
0-40 You can buy at the Swordmanship trainer in New Haven.
40-50 Greater monbats, Skellies, Zombies, Spellbinders which can all be found near New Haven.
50-60 Ettins, Despise and South of New Haven you can these, I would recomend New haven because theres only 1-2 to fight at a time unlike Despise where there are 3-5 at a time
60-70 Earth Elementals in Shame
70-80 Ogres in lower Despise
80+ Ogre Lords lowest level of Despise, Daemons*, Drakes*
*Might be a lil though depending on your other skills
There are many more which you can fight these are just some that I used. You can also experiment with other monsters to see if they help aswell