At The Quilting Patch, we have developed a technique we like to call "Starch Now,Sew Later".
There's lots of reasons to do this -  here are a few...

• Going on holidays? One hour spent prepping your templates at the ironing board will mean youve got them all ready to sew when youve got a little sneaky sewing time. You can even sew in the car / train / cruise ship.
• Having lots of appointments? When was the last time you turned up to a drs appointment and the receptionist said " you can go right in"? Never? Me too. 
  Having your templates prestarched means no more wasted time in waiting rooms flipping through magazines you would never read otherwise.
• Sewing tin too heavy? If youre hesitant to take your project with you because its too cumbersome, this little step will change your mind. If youve prestarched your templates, all youll need to take is a needle, thread and small pair of scissors. ( and the templates of course! ) I carry mine around in a small zippered bag. It fits nicely in my handbag, and Im never held hostage in waiting rooms with nothing to do. 

What you'll need...

• Eppiflex templates
• Fabric ( or scraps that fit the template + seam allowance)
• Fabric Glue pen ( eg Sewline)
• Starch - premade or home made
• Iron

Our Eppiflex templates are made from heat resistant film, which means they are safe to iron on a medium heat setting.
Caution : Continued high temp ironing will buckle the templates, they will still be usable but youll lose the accuracy you've come to love!

OK... so with the caution done, set your iron on a medium heat setting. We mostly use 100% Cotton for patchwork, but it will still iron well on a less than "cotton" heat setting. 

Make up some fabric starch or grab your favourite premade starch. My favourite is "Best Press" but when I dont have any I make my own with "Silver Star" Starch which is still available in IGA stores in Australia. The recipe is on the side of the pack. Follow it AND THEN WATER IT DOWN BY HALF. The regular starch is too strong and will leave white flecks on your fabric and bits on your iron. You can easily store any leftovers in clean jars. 
(I also like to scent mine with essential oils so if you have some, add around ten drops to a 750ml -1000ml spray bottle of starch)

Time to grab your fabrics, Eppiflex templates and glue pen... I am using hexi's in my example. 
On each wrong side of fabric  ( or scrap)  dab a spot of glue and then place the template on the glue, centreing it, as in the pic below.




Trim your seam allowance to 1/4 " or 3/8" if you like a little extra. 




Lay your prepared hexi on the ironing board and give it a little spray of starch and leave for a minute to let the fabric absorb the starch. If you iron it straight away all you'll do is iron the starch off the fabric  The starch wont hurt the template, they wash up great. 



Now fold each edge over  pressing as you go. I find this just gives the edges an even sharper line. 




Your shapes are good to store for later use. The starch will wash out, but for now it means you can throw them into your sewing kit and pull them out at the next sewing stop, be that an appointment or holiday destination!
Will they still need to be tacked?? 
This is a question I get a lot, and the answer depends on how you are going to sew them together. 
If your sewing method requires you to bend the templates in half, then I would say YES to tacking. While starching holds the edges well it wont keep the templates from popping out under pressure!
If your sewing method means you hold the templates flat at all times ( eg ladder stitching) you may not need to tack. 
My suggestion is to give it a go and find what works for you.