Read carefully through their entries on the LSJ:
λέγω
λαλέω
For Koine usage especially, notice the note at λαλέω A3.
First look here. Notice the active aorist indicative. That’s the “normal” paradigm. The LSJ states this in the εἶπον entry:
the present in use is φημί, λέγω…the future ἐρέω, ἐρῶ, the perfect εἴρηκα
For εἶπα specifically, see this usage note:
also aor. 1 εἶπα (“ἔειπα” Emp.17.15, Theoc.22.153), ὅπερ εἶπα as I said, Satyr.Vit.Eur.Fr.39xvii 14, mostly in Ion. Prose, also Men. Pk.128, Herod.3.26, UPZ62.14 (ii B. C.), and the 2nd persons ind. and imper. of this form are preferred in Att., 2sg. ind. “εἶπας” Il.1.106, 108, etc.; imper. εἶπον (on the accent v. Hdn.Gr.1.460) Simon.154, Pl.Men.71d, Men.891, Theoc.14.11, εἰπάτω (“ἀν-ειπάτω” IG22.1186.19 (iv B.C.), but ἀν-ειπέτω ib.1247.13 (iii B.C.)), -ατον, -ατε; 3pl. “εἶπαν” SIG 333.3 (Samos, iv B.C.), later “εἴπασαν” IG7.2225.51 (Thisbe); part. “εἴπας” Philem.42, Aeol. “εἴπαις” Pi.O.8.46, cf. Ael.Dion.Fr.156; in compds. Med. ἀπείπασθαι (q.v.), διείπασθαι (q.v.), but never in good Att.: (redupl. aor. 2 from ϝεπ- ‘say’; ϝείπην only cj. in Alc.55, Sapph. 28.2; “ϝεῖπαι” Leg.Gort.8.15; with ἔ-(ϝ)ειπον cf. Skt. avocam, redupl. aor. of vac- ‘say’; cf. ἔπος):
Eventually. But it can be smart to go as you are doing, and pick the low hanging fruit first. If you try to learn too many similar forms at once, you may find yourself taking more time to learn them than if you had concentrated on what was easy for you, built a foundation, and then gone back and picked up what you missed in review.
The best way to learn paradigms is to review from sentences (in Anki, or wherever) rather than paradigm charts. I’m beginning to believe that paradigm charts should be banished from the classroom except for review. These words need to be glimpsed in their natural habitat before being pinned as specimens.