What should i mainly focus on Rank 27.

I was thinking energy since i all put into ship are decks. then attack
and which should i not put my research into

depends on your playstyle. . .wanna pvp? then weapons/def/hull. If you wanna level, energy/planetary construction. Just my 2 cents

Ok awsome thx for the help.

browse through the "beginner's" forum, many good posts about different playstyles

Should do a bit of both, telling you know, pvp is easy at low ranks.

if you want 4 dominion cannons (and who doesn't? lol) then start pvp now...build your combat reputation before switching to npc and mission (imho)
to aid this weps and hull are very useful...energy is your lifeblood so dont ignore this...and you cant ignore planet buildings to make the most of your colonies.

Well, your nice and early, so you have plenty of flexibility.
You really have 3 main styles.
Slow Rank - Ignore Energy, focus on PVP. Possible to move on from as you will be able to research energy fast should you choose.
Medium Rank - Balance all research. Do whatever you want. Most Flexible.
Fast Rank - Energy, Base (this gets expensive FAST, I wouldn't worry too much at your rank), Structures. Focus on missions. Hard to switch from if you invest alot in engineers, and can take many ranks to get to medium/slow.
However you choose to play, stick with it, if your unsure go for medium to maintain flexibilty.