Spoiler

You can easily increase your concentration to 80 by level 2, over 90 by level 3 (mayhap even 100 already), and guaranteed 100 by level 4.

To do that, enter wilderness on first tile, learn one of your spells, then bookcast it as much as PP's allow you to - light, for example might be even cast twice :). Then, walk to Terinyo, your PP should be full by that time. Again - bookcast your spell there. Travel to were you like to go, stopping in the wildereness every time you have full PP. Repeat the process 'till you reach your First Cave. Repeat the process there too, untill you get your first level-up.

That's all. By the itme you get those 100-250 xps, your Concentration should be trained well enough so that you can easily increase it to desired numbers. Pay attention that it is *very* difficult to be killed by casual monsters on level one (except SMC) even if meeling them with your Staff or even Mighty Fist.

Once you've set your concentration to 100 you can easily go to PC:2 to pillage Ants for level 6+(?) with your Bolt :). You can now kill 4+ of them in a tight corridor with 1d2 castings, giving your enought time to recover till new ones arrive. And, surely, enjoy your guaranteed Vault on the bottom level.

And a decent Cute Dog corpse snack :D