Reddit reviews Princeton Art & Brush Real Value Natural Bristle Brush Set, Round Size 3, Flat Size 4 and 8

I think we have talked about this before but Odorless Mineral Spirits is a solvent that is pretty low in toxicity (you would have to drink it or continually huff it in a small room to get sick from it).

When you said that you are using Cobra oil do you mean that is the brand of oil paint that you are using? If so, you don't need linseed oil. Linseed oil is added to oil paint to extend drying time and lower viscosity. If the paints you are using are water soluble not only will the linseed oil probably give you problems mixing but you could just use water to lower the viscosity of the paint.

I always recommend these artists loft brushes. However if you have a Michael's near you buy them directly from the store. I use them all the time but the store price is $5. I wouldn't buy them for $8.99. However if you are looking to go a step up Princeton is a good brand. I consider brush quality less important than paint quality so really I would just recommend a couple synthetic bristle brushes (Taklon) and a couple hog hair brushes (you can use synthetic hog hair). The Taklon will give you nice smooth strokes and the hog hair will give you texture and make it easier to push around thicker paint.

*note: when you first use a brush you will almost always have a few bristles fall out no matter the quality.

The order of operations you are using to draw will work for oil painting fine.