Welcome to Gaia! ::

I've been playing bass about eight months now, and I've got two issues I would like to resolve:

My first problem is that I try to practice standing up, but after about a half hour or so, my shoulder gets really sore from bearing the weight of my bass. Is there some sort of stance or posture I should try? Should I adjust the strap lower/higher, or get a new strap altogether?

Also, when I play a song with lots of rapid strumming, my wrist sometimes gets really sore. It might have something to do with how I hold the pick, I use my index and middle fingers with my thumb instead of just my index.

Any sort of input would be appreciated, so that I don't develop arthritis within the month.

With the strap if you are using a 2" thick strap, (like a reg. guitar strap) you might want to think about getting a thicker one so the weight is spread out over a greater area, or I think that some straps have like the padding on a back pack. I had the same problem before with my first bass (fender jazz), but I when I switched to a music man sterling it was much lighter so it was better.

As for your picking, are you alternate picking (up and down) or just down only? 

Strap Issue: That used to happen to me also, but I noticed that it only really happens when the strap is laying over my trap muscle. The strap is probably restricting the blood flow that goes to the artery in your neck. (just a guess) I just slid the strap over some. If you feel along your neck you will feel the trap muscle and as you go further out you will feel the end of the collar bone before getting to your shoulder. I put the strap right over that collar bone/shoulder area and it seems to do the trick for me. ALSO, I know this is tough to do with a bass but try sitting with it and finding a comfortable position, then adjust your strap so that the bass is in the same position when you stand. Then lower it as neccisary from there. Getting a wider strap sounds like a good idea too, but I've never used anything wider than 2" so I wouldn't know for sure.

Wrist Issue: Theres a few things I could tell ya about that, but I would really need to see you play to know. First, you are just starting out and I know beginners always tense up when they try to go fast. If you are not relaxed you're gonna end up goin slower and end up sore. Also, I use my index & Middle finger just the way you do so I know the pros and cons of that. TIP: tuck your ring and pinky fingers in instead of flaring them out (like I used to) when you're picking. Having the fingers flared out makes extra momentum you have to fight against evertime your stroke changes direction and thus causing strain on the muscles. Lemme know if that helped at all. idea

My friend says that you should use your fingers sometimes instead of a pick, but only if your fingers are strong enough.

and for the strap, either get a thicker one or one with pads

Cybernetic shoulder....