Hey there all pros

, I'm a warhammer newbie who collected warhammer since I was a kid, but never really had any chance to play "for real" besides the kitchen tabe with my friends. Me and one of my friends decided to start playing warhammer
40k and of course I caught my eye on the notorious greenskin.
I've just bought some of them, probably enough for a 1500 pt army, but the problem is I'm a really big NOOB at building good armies, so therefor I ask if you more proffesional players could help me with my Orkz
I've checked lists here on dakka and on some other forums but it still hard to make a summary of "what's good with what and what isn't"
anyway here's what I've made so far and I thought it would be really HELPFULL if you gents wanted to help me make this army better.
HQ:
Ghazghkull Thraka 225
Big Mek,
KFF 85
ELITES:
5 Nobz (Ghazzie is in this group) 140
x5 'eavy armour
x1 Waaagh! banner
5 Tankbustas 100
x1 Nob,
BS
x1 tankhammer
x2 bomb-squigs
10 Lootas 150
TROOPS
6 Meganobz 260
6x
PK
1x rokkit launcha
2xshoota
3x skorcha
Trukk (Nobz and Ghaz here) 45
red paint
reinforced ram
20 Shoota Boyz 170
1x Nob,
PK,
BS
2x Big Shoota
20 Shoota Boyz 170
1x Nob,
PK,
BS
2x Big Shoota
10 'Ard Boyz 140
1x Nob,
PK,
BS
HEAVY SUPPORT:
1 Battlewagon ('Ard boyz in here) 115
red paint
deffrolla
TOTAL: 1600 pt
So, my plan with this army was that the ranged (shootas, mek, lootas and even tankbustas) would stand back a bit, while my two trukks drives close into the enemy lines and Ghaz and his Nobz and the 'Ard boyz would cause havoc amongst the enemies. If any enemies would come close to my ranged to quickly my ranged would be dead in a minute so therefor I will have the Meganobz sort of "protect" them from incoming enemies, I think I might use the Tankbustas for hard-killed tanks and vehicles.
So basicly when Ghaz and his Boyz is fighting the slow or ranged units up in the enemy lines, my Meganobz would stand against and cleave fast incoming enemies while those are spammed by Lootas and Shootas.
However I'm not really sure if this works and that's probably why I need your help you see I still get the feeling that if I don't make this tactics when playing I'm pretty fethed... I consider replace the tankbustas and meganobz with a BIG squad of Kommandos that also helps Ghaz and the others do their thing but how will that work out for my ranged units?
My friend that I mentioned earlier is playing Tyranids, (with wings!) and I certainly won't give him the pleasure to win every time

but
ofc I want my army to be fair against most kinds of armies. So please help me!