Clown loaches will grow too big for a 30gal, they also prefer tanks with a lot of width rather than height. Personally i would work on some of your current stocking before you get any new species of fish;
10 gal, 2 gal fry tank
1 red honey gourami
3 glolite tetras
2 orange tetras
4 female guppies
3 male guppies
2 cory catfish
1 mystery snail
Tetras prefer to be in groups of at least 6+ of the same species due to being shoaling fish, so i would add another 3+ glolites and whatever your orange tetras are too.
Really you should have 2-3females per male with livebearers like guppys as this will cut down on harrassment between the males and females, so i would add another 5+ female guppys bringing you to a total of 8, although more females would be better if you can(if you don't want to buy anymore female guppys i would separate the males and females or rehome 3 of the males)
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Corys do best in groups of 3-4+ of their own species, so adding another 2+ to your current couple would be good depending on what species they are; corys prefer a sand or fine rounded gravel substrate(sand is best though im my experience), so if you havn't already bought substrate for your tank i would go for some sand substrate(its also generally easier to maintain/keep clean as well in comparison to gravel).
I'm no expert on gouramis and snails though so i couldn't comment on those, but if you follow these current things your stocking in your new 30gal should look more like this;
30gal stocking;
8 female guppys
4 male guppys
4 corys
6 glolite tetras
6 orange tetras
1 honey gourami
10gal;
free
2gal fry tank;
This still leaves you with a fair amount of space for new fish species, although i really wouldn't recommend clown loaches as they are not suitable for your tank either way- this stocking though will completely free up your 10gal to do with whatever you want with it as wel;
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What sorts of fish species are you into? Do you know what types of corys you currently have? Have you considered in getting another tetra species after you add to current species numbers?