Masking Sheets

Two materials come to mind - for either I would copy said page of instructions to work from, just in the event you have any little accidents while cutting;

Lay down some overlapping masking tape, or some Frisket Film (masking film) on a hard, flat surface (glass sheet, large plate....).

Put your copied instruction sheet over the masking material (you may want to tape it down to prevent any unwanted movement) & cut the mask with a fresh blade - voilà.

Masking tape you will most likely have, Frisket film can be found online easily - usually in artist supplies shops or airbrushing shops.

I assume you are in the US?

A technique I have tried in the past with a certain degree of success is to photocopy the pattern, cut out the relevant areas and spray the backside with aerosol spray adhesive. This does work as an effective mask if the spray adhesive is given ample time to dry so it isn't too sticky.  You also have to be careful to spray up thin layers of paint and not to soak the paper with paint. 

The draw backs I found with this technique is that the paper doesn't conform well to anything but flat surfaces and if you don't let the spray dry to the right point, it may leave residue on the model.  I eventually abandoned this technique for more traditional ones like the one detailed above.

One thing I tried that I would NOT recommend is the pressure sensitive labeling material made for computer labels.  They sell it in 8.5 x 11 sheets- one big sheet so you can cut odd size labels.  I cut some masks with that.  Got it too wet (with paint) in some areas, the paint soaked through and combined with the adhesive.  Made a real mess- the masking paper was glued to the model.

You don't need masks! When I do my camo I just use either low tack masking tape or Post It Notes to mask any straight lines such as that of a German Splinter pattern. Use the kits painting instructions as well as photographs for line placement references...then just lay down the masking.