When optimising for a particular keyword / keyword phrase it is important to vary your anchor text.
Naturally occurring links to any given page will always come from varied anchor text. For Google to rank you highly your links should look as naturally occurring as possible and therefore, you're going to need to imitate this by varying your anchor text.
For example, it isn't likely that the whole world will get together and link to your content with your keyword anchor text 'ice-cream sandwiches' (that'd just be weird). Some will link to your url – ice-cream-sandwiches.com – others will link to your company name or brand name – Sweet Sarnies Limited – and probably loads will use 'if you want to try the latest craze in melting lunch items click here'. This is all good, naturally occurring anchor text that you should be dropping into the mix every now and then on your campaign. Even though 'click here' is a very low value SEO term it does tempt people to click, so its value in terms of click-throughs, as well as in terms of making the link seem naturally occurring, is pretty high.
Working Out Your Anchor Text
So, besides the obvious, there are a variety of means you can employ to arrive at varied keyword phrases to use as anchor text. For the most part, they're pretty darn simply to do.
Every time we perform a search, Google gives us a few alternative options. Google seems to know what we want better than we do ourselves these days and that is a god send to the overworked SEO bod. As you begin to type your keyword phrase, Google Predict will give some alternative options. If you're getting those, that means your customers are too, so it's worth using a few if only to catch the easily distracted.
After the search performed Google will give you a list of search topics related to what you just looked for and these are anchor text gold as well.
Google Insight will give you information and trends on search terms in a scary amount of detail, all of which can be used to your advantage.
Also, don't forget to take a look at your natural inbound links, if you have some. What phrases do people use to link to your content? Our customer behavior can tell us a lot.
There are any number of other ways to determine anchor text but this should start you on the road. However you come up with varied phrases, just make sure you do; using the same anchor text all the time will flag with Google as unnatural activity and see you penalised, then no-one will be able to find your ice-cream sandwiches!