One advice: DO NOT use PlayDoh as your masking for camo. It may leave behind stains and bits of PlayDoh - especially on Zimmert surfaces of armor kits. I highly recommend you use blue poster tack or Silly Putty instead. PlayDoh cannot be reused again and will dry out over time.
DITCH THE PLAYDOH !!!!!!!!! They have no place as masking agent for camo in this hobby. You'll thank me later………..
Blue poster tack and Silly Putty will not dry out and can be used over and over again and still retain the tackiness without leaving stains behind after airbrushing. I'm still using the same blue poster tack from the last 8 - 10 years now. Keep it stored properly and it will last you a long time. I store my blue poster tack in a small medicine dose cup with a lid. Silly Putty can be stored in its egg container it comes in.
Well…. that rules out an F-4 Phantom. Stencil decal hell that one is. ROFL!
You can't go wrong with any Tamiya armor and ship kits. 1/350 scale ships are going for really stupid money for them. 1/700 ships are smaller and affordable. Some can be built waterline or full hull.
Aftermarket parts can be expensive. I don't get involved too much in them unless I have to or need it. Although Quinta has fantastic raised instrument panel decals. Masks are well worth it especially hose with greenhouse canopies of Zeroes, Helldiver, Dauntless, etc… Making and masking your own canopy with Frog yellow painter tape can be challenging and time consuming.
Why not try a new skill building a biplane kit like a Stearman kit by Revell or a 1/32 scale Academy Sopwith Camel kit and rig it with EZ line or black thread. 1/72 scale biplanes are tiny, 1/48 scale biplanes are smaller compared to a 1/48 scale WW2 fighter. 1/32 scale biplanes are a little better to work with due to their built up size equal to a 1/48 scale aircraft.
Aftermarket decals on the other hand are simply awesome! Sometimes the kit's supplied decals are blah and you want something different. NATO Tiger Meets and Commemorative tail schemes are very attractive for jet aircrafts. I've got several in my stash. The best part? You don't have to weather them or load them up with missiles/bombs and what not.
Aftermarket decals of WW2 bombers and fighters have a wide range of markings from different squadrons/bomb groups: Bloody 100th, Zodiac Liberator bombers, etc… WW2 fighters like Tuskegee Red Tails, Blue Nosed Bastards of Bodney, Zemke's squadron, etc…
Auto kits are fun builds too. Tamiya auto kits are expensive. I like MPC and Monogram kits personally. Revell aren't too bad either. AMT can go either way depending on the kit. Make sure you don't toss any spare parts/tires/ rims/wheel backs. Save them all. Once you save a bunch of different parts, you can reuse them to customize/kit bash any kit anyway you want. Auto aftermarket stuff are worth it if you want to enhance the engine with distributor with wires, custom rims, complete engines, etc…
Maybe you want to try your hand on an big rig with or without a trailer. Maybe a fire truck kit or a motorcycle kit. There's something for everyone.