I'm a level 54 soon to be 55 who needs to get 50 attack. Here are my stats.

 

43 attack

50 strength

41 defense

44 health

And i need to kill 100 moss giants for slayer. So with rune platebody rune sword and adamant helm shield and legs where should i level up my attack?

finish the slayer task and then get another one. that what i would do. if anything after kill the hill giants, then stay and kill some more.

I would either keep going with slayer, or kill something that you can camp (ie: stay for a very long time at). I apologize for the dodgey response, I'm not up with all the new training spots. If you are looking for exp, I would take a look at experiments, rock crabs or something from the stronghold of security. If you are looking for a bit of money on the side, I would stick with hill giants or take a look at baby blue dragons. Banshees in the slayer tower are another good alternative. Pick up and bank things like big bones, baby dragon bones and all herbs (use the Guam and tarromin yourself to level up herblore). If you are simply looking for something you never have to worry about dieing to, competing with someone else for, or that is not click intensive, I would try the elemental under the seers village building next to the bank. I trained from about your levels to 60+ all levels there and only saw one other person the whole time, and he was doing the quest. Don't expect a huge infusion of cash from there, though. Feel free to add me on runescape, I have some assignments to do over the next few days but am happy to help you out ingame at most times :)

 

EDIT: I would strongly reccomend getting a set up similar to these options. I have no idea about your budget, so I'll post them from best to worse, and pick out what suits you.

 

Amulet of glory > amulet of power > amulet of strength.

Rune full helm > rune medium helm > addy full helm

Rune Plate > Rune Chain

Rune Legs > Rune Skirt (the same bonuses but cheaper) > addy legs

Rune Kite > Rune Square > Addy kite.

Rune scimitar > Rune weapons in general.

Any cape will do you fine at the moment

Use the best lumbridge ring you can, it could help you with drops if you can use the low-alchemy function.

For boots, Rune boots > Addy boots > Climbing boots.

 

EDIT2: Damn iPhone. If there's any grammatical or spelling errors, sue me.

For boots, Rune boots > Addy boots > Climbing boots.

at a low budget climbing>all but dragon.

 

that being said, stick with slayer. It'll help you in the long run. I would kill the hill giants kind of near castle wars (no clue where exactly I just remember training there at low levels) and bank the bones etc. you really do need better gear, and slayer should help. Good luck.

^ You forgot gloves... <_<

 

It's pretty unlikely that you have completed RFD up to the rune gloves point, so here's what you should take:

Rune Gauntlets > Other gauntlets > Safety Gloves > Green d'hide vambs