One way to try is to start by writing short passages and translating them into your invented language. As language irregularities essentially arise from "mistakes" made over a period of time, I find that they tend to introduce themselves.

Of course, this doesn't work for everyone. I just find it a useful starting place.

It's like, if you are drawing an imaginary map and you use your opposite hand (in my case, my right) then you can get the jagged coastline much more easily.

Anyway, I had a lexicon and I thought I'd lost it. But I didn't, so here's some I did today.

Magorho aanecke. Iishiy borakhete amek; yibushoor iu y'azhorli yikhrene aa-orak. Karhi phi-aunazh aanecke yat, ai gereshe luaah makishiy, d'pia phori-ia yemek. Ai Naikol bushoor criphikei tishik. Raisha aameshe ebushoor. Aa phrardihe mek - Shaina aamek.