Here's a recent discussion where I was discussing strategies for relay design - as the below will cover, I suggest an approach that is "majors-first or extra strength".
You can also see this at:
http://forums.bridgebase.com/index.php?showtopic=18143&st=0&#entry178389

In looking at 1M-2C I found a lot of hands were stopping at 3NT, assuming responder was not starting with a M fit at go. Thus it seemed the ideal was:
2C: Extra major length or length in OM or big hand?:
--2D: No
----2NT: Anything shapely to tell me about?
------3NT: No

So it wasn't just strength or shape first, it was tell me if you have extra strength or if you have shape that I should know about first. And, in a majors first philosophy I believe that shape should be length in the majors.

So for example, one can have, after a 1D opener:
2C: Please bid one under your major or show extra strength.
--2S: No major, no extra strength
----2NT: Anything shapely to tell me about?
------3NT: No

Or perhaps on these sequences, 3C should be no, and 3NT showing some shapely hand (better).

If I was trying over a strong C and negative reply of 1D, something like Relay-Kokish could be tried:
1H: Do you have a five card major or extra strength?
--1S: No
----1NT: Shows some range (or, better, re-asks if 1C-1D--1NT covers all less than 20)
----2C: re-asks
----Rest: Hs
--2C: 5Ss
----2D: re-asks
----2S: shows the range for 1H-1S-1NT
----Rest: if below 3S shows Hs, 3S and above shows S fit.
--2D: 5Hs
----2S: re-asks
----2H: shows the range for 1H-1S-1NT
----Rest: H fitRest: Extra values, showing hand type if not 1NT bid.

After the strong C opener, there are many design options following a majors-first or extra strength approach. For example one could try after 1C:
1D: negative, not 5+Ss - now "Relay Kokish" above becomes easier (so Easy Over Kokish)
1H: 5+Ss, fewer than 4Hs. 1S now relays.
1S: Any game force without a five card or longer major. 1NT relays, see below.
1NT: Game force with 5+Hs.
2C+: 2C and some of the higher bids are used to show 5-4+ in the majors.

After 1C(strong)-1S(GF, no five card major)--1NT(relay), following the same approach:
2C: no major, no extra strength.
--2D: relay
--2NT: Anything shapely?
2D: 4Hs, 2H re-asks.
2H: 4Ss, 2S re-asks.
2S+: Extra values, no major, shows hand type.