Starting out to learn anything new or to increase skills and knowledge, including maintaining your skis or snowboards, there is always an over abundance of information and uncertain choices that can numb or paralyze anyone enough to not take the first step.
✴ You need to start somewhere and choose easy tasks
✴ Take your time and be patient
✴ Learn as you go and from your mistakes
✴ Don’t be afraid of making minor mistakes. They can be fixed.
Determining what capabilities or level of tuning you are after will help decide on tuning or other tools. What level tuner are you and want to be; Leisure/Casual, Performance or Serious?.
If you looked at building a tool kit whether it’s files, diamonds guides, brushes, waxes, etc as you looked at building your quiver of skis, you wouldn’t necessarily get everything you can to start. There are simply too many variables to grasp without time and experience, cost and other considerations. As with skis and other gear, you can always buy more and there are various grades or calibers of tools. For the recreational skier and tuner, getting every one of the finest tools may be overkill and an unnecessary expense. But if you appreciate fine tools, and start out purchasing them, it’s hard to go back to lessor caliber as you become spoiled.
For the ‘all mountain’ capabilities for main files & diamonds which you can build on, we suggest:
1) bastard or 2nd cut file-for edge sharpening, beveling and setting edge geometry, coupled with guide. The coarser the file, the faster the cut and filings stream off easier.
2) panzer/body file-for removal of side wall (edge off-set), quick removal of edge when establishing edge geometry or removing excess base material. Also great for plexi scraper sharpening.
3) 200 & 400 grit diamond-for de-burring, maintenance sharpening, finishing and polishing edge
4) aluminum oxide stone-inexpensive ‘beater’ stone for knocking down case/work hardened edges, de-burring, knife sharpening, misc tasks
5) gummy stone-de-tuning and rust removal
6) base and side edge combination guide-used to secure files, diamonds and stones accurately to set edge geometry (bevel angles) and can be used for maintenance sharpening with diamonds or stones
For starting out and I’d bet for the majority of recreational tuners (and if you’ll also need other tools), a Tools4Boards Deluxe Tuning Kit or SuperStation, coupled with a 
diamond and gummy stone will be more than adequate, can be built upon and is a great value. The 3 in 1 Xact or Razor in our kits are solid and highly versatile. Later, if you decide to purchase more dedicated angle guides, for side and/or base edges, the 3 in 1s will still be a nice tool to keep handy for sidewall planing, scraper sharpening, bevel measuring and as an additional guide. Over time you’ll realize that having more than one guide expedites each job, especially when you are maintaining several pairs.