TLDR - Read the yellow highlight section. Good points made by all. Having Arms Companion would be great as it includes Wrestling (Grappling crits) and Tackling (Ram/Butt/Bash attack table) as two more optional "Martial Arts" styles at same cost of MA. One common theme is that people hear "Martial Arts" and immediately think "Little man in robes, jumping and kicking all over the place." Any fighting style (martial) that is studied and improved upon(art) is a Martial Art. This includes boxing, wrestling, aikido, fencing, kicking styles, throwing styles, grappling styles, etc.
There are Large and Super Large crit table for Martial Arts. That doesn't necessarily mean the halfling threw the dragon over his shoulder, but perhaps he was able to target pressure points, nerve clusters, or wiggled his own body in such a manner that his opponent fell from his own momentum (Aikido).
Background Options: I always try Skill at Magic just once. There are some nice stat bonuses there and some cool things even for non-spell users. I believe Skill at Arms table has +25 to Adrenals. Always a great bonus to have as it saves you a ton of DP in Adrenal ranks across the board.
Sweeps/Throws vs. Strikes: This is going to be personal preference. Personally, I like sweeps and throws as they produce Unbalancing crits which do nasty things like extra broken bones and "wind knocked out of target" extra stuns. And a prone foe is a good foe. The heavier armour types are especially vulnerable to the Sweeps and, as they are harder to damage with weapons, using that heavy armour against them is a great advantage/equalizer. Where weapons can't penetrate the heavy armour, you can do a lot more damage. I think there are simply more advantages with Sweeps than with Strikes. The results of the unbalancing crits put a lot in your favor - prone, stun, skeletal damage.
Adrenals: I'm a fan of Adrenal Speed with Sweeps/Throws. If I can get two sets of Unbalancing crits on my target it's fantastic. I'll take Adrenal Strength if I'm going to focus on the Strikes instead. A token 1-rank in Adrenal Landing at the very least. It's saved my hide a few times and made me wish I had it plenty of other times.
(Note - If you take Adrenal Balance, take Tightrope Walking too. Why not?
And depending on your GM, Grappling Hook and Rope Mastery. Some GM's are strict.)
Meditations: Ki, Healing, and Sleep are nice ones to have.
Ranks of Sweeps or Strikes: Whichever is your primary means, 2-ranks per level, every level until you hit 10 ranks. The "other" style, 1- per level if I have a stray 1 or 2 DP leftover and I don't know where to put them. I usually focus up to rank 2, but I'll throw some into rank 3 and 4. I wouldn't buy my "back-up" style all ranks, every level. Just throw 1 or 2 DP at it. It's also good to have as a back up if you break your arm, you can use strikes to kick and maybe not have a penalty.
After 3 levels (I've assumed you use Adolescent Level-0)
Sweeps
R1: ******** (8 )
R2: ******** (8 )
R3: **** (4) Once you've reached 10 ranks in R1 and R2, dump the points into
R4: **** (4) R3 and R4 as you'll need more hitting power as your foes are
stronger now. Lower level NPCs, R1 and R2 is good.
Strikes
R1: ** OR * At lower levels, you'll be using your primary attack. Once you've
R2: ** OR * mastered (maxed out Sweeps) you can focus those DP in Strikes.
R3: * Should be by level 9 at this point.
R4: *
I would take 1 rank per level in a ranged weapon too. Nothing wrong with a bow or crossbow to soften up the enemy. With the stats you have, you won't need a lot of ranks to be decent at it. Just don't waste DP on buying 2 ranks per level.