Agree with Jon that Brun water is fantastic.
As far as equipment goes I've been using cheaper (~$20) meters and treating them as semi-disposable (I'm on my second one now). The more expensive ones I'm sure are more precise but it seems to work for me.
1) Set up my water profile with Brun Water during the recipe design phase. I typically use a blend of RO and tap water and CaCl & Gypsum.
If you don't have a water report, have bad water, or are having a tough time getting the inputs you need for Brun Water starting out with RO water may be a good option.
2) Calibrate my pH meter with buffer solution on brew day.
3) Take a reading 10m into the mash (cooled sample)
4) If pH is higher than my mash target I add a bit of 88% lactic acid using a medicine dropper and retest.
4b) If pH is too low I add a bit of Baking Soda to raise it.
5) I recently started messing around with the German method of mashing a bit higher (5.5 or so) for better conversion then acidifying in the boil to hit 5.3 or so. Most people just worry about a proper mash pH which should set up a nice boil, fermentation, and final pH.
6) I'll measure pH again after fermentation is complete and compare it to what's typical with the style and what I predicted. A proper kettle pH and a healthy fermentation should do the trick although Jim used acid in his pale ale in the keg to take it down (to 4.3 IIRC) and has enjoyed the results. Usually finishing at or below 4.4 is desired but there are exceptions.
Resources I would Google:
1) Weyerman pH in the Brewery for a nice slideshow (note the one slide about pH for style is a typo - they mean final pH not mash ph)
2) Brau Kaiser pH - Kai has a great write up on everything pH related from a German perspective.
3) Again, Brun Water. The creator of the software, Martin, is active on this forum and a great resource.