woodland bow or silver?
I don't see much reason to lug around a ~24 feather (? don't remember) bow with my measly 34 strength.
What would you say is best for a thief with these mid-high 30s stats in fatigue and strength (currently level 6). I don't see the purpose of using a silver bow other than stats show it hits harder? It is the silver arrow that hurts the resistant beast, not the bow.
The only way I know how to increase strength is in combat (using DP Archery).
I think my combat skills really are lagging behind. I have Setsuna training mod but that can get monotonous hitting a target over and over bare-fisted to gain h2h and by extension, strength. I set up one of my new Logitech G110 keyboard macros to repeatedly press "." to auto attack while afk. Further testing will have to be done for stability. I had the game crash while afk a couple times just staying inside Chorrol and hitting the target board.
Which bow you use is of course your choice, but having
something silver or enchanted on hand is always highly advisable in TIE, where more enemies (vampires, liches, etc.) are resistant to normal weapons. Personally, I always carry ~15-25 silver arrows (more if I know I am raiding a dungeon full of Undead) plus a silver dagger. I stick to a lightweight mundane bow, however. For many levels that was the bone bow I acquired from a goblin as I was just exiting the sewers; now it is an elven bow, which has proven much sturdier in long fights.
Silver bows
do hurt resistant enemies in Vanilla, even when used with ordinary arrows, strange though that may be.
If you want to get your strength up without grinding away, try picking fights with weaklings whenever you come across them. I've started going out of my way to use that trusty silver dagger to mow down rats, mudcrabs, shoats, and poorly-armed, poorly-armored humanoids. Otherwise, there are alternative training mods - Duke Patrick has a couple published for, I think, blade and marksman skills - or you could use Realistic Fatigue, which slowly increases your Strength-related skills when you carry a heavy load. Some leveling mods also award minor increases in strength when you increase related attributes. However, these other non-TIE methods of increasing Strength are off topic in this thread; you might wish to create a separate thread if your concerns were not answered here.
Of course, you could always just increase the relevant skills at trainers - who will train you as much as you like in the most recent versions of TIE. And if I were you, I wouldn't worry too much about your "combat skills" if your Marksmanship is increasing apace. With proper planning, preparation, and chicanery, you can almost always avoid a fight at close quarters.