You get access to the Gene splicer very early in the game, but for much of the game you only have the basic gene splicer, which is pretty limiting. I have a few tips for this period of the game:

1) Don't clog your seed inventory with seeds from areas you can't plant yet. You can go get mountain seeds on day 1, and then they will sit in your seed box for half the game. Once you unlock the marsh you can decide if you want to start splicing those, keep working on plains seeds, or split your attention

2) Don't try to be a perfectionist early in the game. Gene splicing gets 14x easier with the advanced splicer, and you only need one perfect seed rather than 14, so it's kinda 196 times easier. try to get a seed with regrowth and as many qualities as you can. it's very easy to add 2-3 qualities to the right part of a genome, just make sure you change the *last* gene back to orange to reactivate regrowth

3) Do try to get the advanced Gene Splicer as early as possible. You need to get your relationship up with Zaheen. Triggering the quest requires sleeping, so don't forget to take naps every few days, even if you substitute food for sleep (you should). The Recipe requires a basic gene splicer, so don't bother trying to save the scrap by using Wyatt's, get yourself one when you can afford it. It also requires all the bugs, which will require swamp boots. it also helps to have unlocked the rest of the mountains with dynamite. I honestly found the plains insects to be hardest to complete, and it wasn't too hard to just focus on bugs for a few days

4) A little off topic, but I personally recommend not crafting a bunch of watering stations. craft one and carry it around with you, you'll save 30ish scrap(and a bunch of wood), and placing a machine to use, then picking it back up is actually pretty convenient. You can do the same with your first sprinkler

5) I'm not sure how often plants want to be watered, but it's all the freaking time. I suggest avoiding the "needs water" trait early if you can

So, now on with the splicing!
some basic tips:
1) the top seed uses the right part of it's genetics, and the bottom seed uses the left part, so switching which seed is in which slot completely changes what genes you get.
2) You can move the scissors left and right to pick where yo splice the genes.
3) In case it isn't obvious the traits are all just a color pattern. right color means right traits. It is possible to combine 2 worthless seeds into a great one, and that means:
4) plan ahead. It is not possible to splice into the *middle* of a seed's genes. An almost perfect seed that has one gene wrong in the middle may be significantly harder to make perfect, than something that only has half the traits you're looking for. because you can splice to either end, start building your perfect seed from the inside out, and then look for seeds you can graft onto it in order to make the next wrong gene right
5)You may need to *lose* a good trait in order to fix an interior gene, and then work on getting it back after, this is fine. remember to work towards a specific goal, and not get caught up on each seed being better than the last, or you'll get nowhere

Without further preamble here is my road map to, in my opinion, the best possible plant seed

Any gray bar can be either color, it doesn't matter.
The gray stars are "optional". "Loves Fertilizer" is a meh trait, and the blue ones on the right side can be added in later. You should be fine with any of those being the wrong color on your first splice.
You may notice the orange star marks a "required" gene that doesn't show up below. Having this be orange prevents the negative "requires water" trait, which you probably want to avoid

What this seed has going for it:
It has "Regrowth", which means it reverts to the seed phase when you harvest. once a field is planted in never has to be planted again, you don't have to turn half your harvest into new seeds, and you don't need to keep half your inventory full of seeds for your fields. Regrowth is my favorite trait
"Growth Rate 2" about halves the amount of time for the crop to mature. it gives you a larger and steadier supply of produce
3/4 Qualities: Qualities involve blues in the right most block. they raise the star quality and therefor the price of your crops. the 4th one conflicts with regrowth, and you'll make more money off not having to turn crops into seeds than you lose off the 4th quality

What this seed lacks:
"Yield 1" conflicts with "Growth Rate 2", and the latter is *much* better
"Yield 2" and "Yield 3" both conflict with regrowth. Regrowth is amazing, but this seed isn't technically the highest value in the game, see below for more info

Once you get even a single seed with this set up, you can use the advanced gene splicer to clone these genes to another species. Simply put the new species seed at the top, the "perfected" seed in the bottom, and then slide the splicer all the way to the right, and BLAMMO! perfect seed for the new crop.

You've got some time on your hands, and you want to *maximize profits*. You're willing to constantly water your crops, and go through all the hassle to make new seeds, well here's the crop for you:

What this crop has going for it:
Growth Rate 2: grows fast
Yield 2+3: this means that you'll harvest 9 items instead of 4
all 4 qualities: From my testing each quality is a 50% increase in crop price, so all 4 *triples* the price of the finished good.
That means that if you grow this bad boy your profit will be almost 7 times as much as if you were growing lame "no traits" seeds

What this crop lacks:
This crop has "requires water" I have found that even with an auto sprinkler this negatively impacts the growth rate. 2 auto sprinklers set to every 3 hours might do the trick, or maybe not, I don't know
No regrowth is sad, so much more micro-managing of your fields. by the time you're far enough in the game to have this you probably have loads of cash, and want to be focusing on romance, not on farming
It is very complex. Almost every single gene is needed to pull this all together, so you'll be doing a lot of combining.

Quantity over quality:
Here's what you need to do for the achievement. the seed is pretty useless otherwise

The last trait worth mentioning is grows anywhere. It allows you to grow the crop outside its normal biome. if you got them early you could probably do some fun sequence breaks or something *shrug*. Mountain crops are worth almost double what a plain crop is worth, however "grows anywhere conflicts with "yield 3", "Yield 1" "Growth Rate 1" "growth rate 2" "regrowth" and "extra fresh", it doesn't seem worth it, but here's a picture of the requirements (sorry it's cropped funny, game doesn't display it well at the bottom of the screen)

Animal splicing has a lot in common with plant splicing, but there are some important distinctions.

1) Animals have the "star quality" traits, but they don't seem to do anything as the products don't inherit the quality.

2) you can gene sample your animals by right clicking on them when they have a product ready. you get genes instead of the product.

3) There is a "rare drops" gene. it is really the only gene of any importance. An animal that can't produce rare drops isn't worth your time. Fortunately "rare drops" is super easy to get, only require the 1st and 4th genes be blue, so 1 in 4 wild genes should have rare drops, and it should be very easy to splice using a basic splicer.

4) For animals there really is 1 "best" genome, so you can make a perfect animal, and then clone it without worry.
Like I said above, "rare drops" is all you really care about, everything else is gravy, so I didn't individually label everything as optional.

Qualities: do they do anything? Not that I've found, but they're positive so I included as many as I could
Yield 1: slightly more stuff (yield 2 conflicts with rare drops)

Grows quickly: sounds great on paper, but I generally tended all my animals in a big batch, so some being done early didn't help. It's very complex to get, which probably means later in the game, and I think it's peak value is if *every* animal you own has the trait, so you'll really reach "post scarcity" before this reaches its full potential.

eats flowers: Flowers are the cheapest/easiest food source to get, so this trait is actually pretty handy, plus I *loved* when I finally got 100% of my animals eating the same things. if the right gene is blue it's "eats wood" which is fine, but clearly worse. the right one being blue is "eats stone", which is also fine, but conflicts with "grows Quickly" if both are blue you get "eats minerals" (like niter, copper etc) which is very bad, don't do that

Docile attitude: if you like taking your pets for a walk this makes them follow better. swapping the orange gene to blue makes it "wild" which does the opposite. since my incubator is right by my pens, I never needed to walk an animal more than 10 feet. Early in the game I had a wild one, and it never inconvenienced me in any way